Merge branch 'master' into docking

# Conflicts:
#	imgui.cpp

docs/CHANGELOG.txt

@@ -59,6 +59,11 @@ Breaking changes:
       Before:  BeginChild("Name", size, 0, ImGuiWindowFlags_AlwaysUseWindowPadding);
       After:   BeginChild("Name", size, ImGuiChildFlags_AlwaysUseWindowPadding, 0);
    Kept inline redirection enum (will obsolete later) so existing code will work.
+ - BeginChildFrame()/EndChildFrame(): removed functions in favor of using BeginChild() with
+   the ImGuiChildFlags_FrameStyle flag. Kept inline redirection function (will obsolete).
+   Those functions were merely PushStyle/PopStyle helpers and custom versions are easy to create.
+   (The removal isn't so much motivated by needing to add the feature in BeginChild(), but by the
+   necessity to avoid BeginChildFrame() signature mismatching BeginChild() signature and features.)
  - Debug Tools: Renamed ShowStackToolWindow() ("Stack Tool") to ShowIDStackToolWindow() ("ID Stack Tool"),
    as earlier name was misleading. Kept inline redirection function. (#4631)
  - IO: Removed io.MetricsActiveAllocations introduced in 1.63, was displayed in Metrics and unlikely to
@@ -87,14 +92,33 @@ Other changes:
 - Windows:
   - BeginChild(): Added ImGuiChildFlags_ResizeX and ImGuiChildFlags_ResizeY to allow resizing
     child windows from the bottom/right border (toward layout direction). Resized child windows
-    settings are saved and persistent in .ini file. (#1666, #1496, #1395, #1710)
+    settings are saved and persistent in .ini file. (#1710)
   - BeginChild(): Added ImGuiChildFlags_Border as a replacement for 'bool border = true' parameter.
+  - BeginChild(): Added ImGuiChildFlags_AutoResizeX and ImGuiChildFlags_AutoResizeY to auto-resize
+    on one axis, while generally providing a size on the other axis. (#1666, #1395, #1496, #1710)
+    e.g. BeginChild("name", {-FLT_MIN, 0.0f}, ImGuiChildFlags_AutoResizeY);
+    - Size is only reevaluated if the child window is within visible boundaries or just appearing.
+      This allows coarse clipping to be performed and auto-resizing childs to return false when
+      hidden because of being scrolled out.
+    - Combining this with also specifying ImGuiChildFlags_AlwaysAutoResize disables
+      this optimization, meaning child contents will never be clipped (not recommended).
+    - Please be considerate that child are full windows and carry significiant overhead:
+      combining auto-resizing for both axises to create a non-scrolling child to merely draw
+      a border would be better more optimally using BeginGroup().
+      (until we come up with new helpers for framed groups and work-rect adjustments).
+  - BeginChild(): made it possible to use SetNextWindowSizeConstraints() rectangle, often
+    useful when ImGuiChildFlags_AutoResizeX or ImGuiChildFlags_AutoResizeY. (#1666, #1395, #1496)
+    Custom constraint callback are not supported with child window.
+  - BeginChild(): Added ImGuiChildFlags_FrameStyle as a replacement for BeginChildFrame(),
+    use it to make child window use FrameBg, FrameRounding, FrameBorderSize, FramePadding
+    instead of ChildBg, ChildRounding, ChildBorderSize, WindowPadding.
   - BeginChild(): Internal name used by child windows now omits the hash/id if the child
-    window is submitted in root of id stack of parent window. Makes debugging/metrics easier
-    and shorter to read in many cases.
+    window is submitted in root of id stack of parent window.
+    So "Parent/Child_XXXXXXX" becomes "Parent/Child" when in root of id stack.
+    Makes debugging/metrics easier and shorter to read in many cases.
   - Popups: clarified meaning of 'p_open != NULL' in BeginPopupModal() + set back user value
     to false when popup is closed in ways other than clicking the close button. (#6900)
-  - Double-clicking lower-left resize grip auto-resize (like lower-rightone).
+  - Double-clicking lower-left resize grip auto-resize (like lower-right one).
   - Double-clicking bottom or right window border auto-resize on a singles axis.
   - Use relative mouse movement for border resize when the border geometry has moved
     (e.g. resizing a child window triggering parent scroll) in order to avoid resizing
@@ -182,6 +206,8 @@ Other changes:
 - ImDrawList: Added AddEllipse(), AddEllipseFilled(), PathEllipticalArcTo(). (#2743) [@Doohl]
 - ImVector: Added find_index() helper.
 - Demo: Added "Drag and Drop -> Tooltip at target location" demo.
+- Demo: Added "Layout -> Child Windows -> Manual-resize" demo. (#1710)
+- Demo: Added "Layout -> Child Windows -> Auto-resize with constraints" demo. (#1666, #1395, #1496, #1710)
 - Backends: GLFW: Clear emscripten's MouseWheel callback before shutdown. (#6790, #6096, #4019) [@halx99]
 - Backends: GLFW: Added support for F13 to F24 function keys. (#6891)
 - Backends: SDL2, SDL3: Added support for F13 to F24 function keys, AppBack, AppForward. (#6891)

imgui.cpp

@@ -432,6 +432,8 @@ CODE
                           - likewise io.MousePos and GetMousePos() will use OS coordinates.
                             If you query mouse positions to interact with non-imgui coordinates you will need to offset them, e.g. subtract GetWindowViewport()->Pos.
 
+ - 2023/11/07 (1.90.0) - removed BeginChildFrame()/EndChildFrame() in favor of using BeginChild() with the ImGuiChildFlags_FrameStyle flag. kept inline redirection function (will obsolete).
+                         those functions were merely PushStyle/PopStyle helpers, the removal isn't so much motivated by needing to add the feature in BeginChild(), but by the necessity to avoid BeginChildFrame() signature mismatching BeginChild() signature and features.
  - 2023/11/02 (1.90.0) - BeginChild: upgraded 'bool border = true' parameter to 'ImGuiChildFlags flags' type, added ImGuiChildFlags_Border equivalent. As with our prior "bool-to-flags" API updates, the ImGuiChildFlags_Border value is guaranteed to be == true forever to ensure a smoother transition, meaning all existing calls will still work.
                            - old: BeginChild("Name", size, true)
                            - new: BeginChild("Name", size, ImGuiChildFlags_Border)
@@ -5716,22 +5718,43 @@ bool ImGui::BeginChildEx(const char* name, ImGuiID id, const ImVec2& size_arg, I
     IM_ASSERT(id != 0);
 
     // Sanity check as it is likely that some user will accidentally pass ImGuiWindowFlags into the ImGuiChildFlags argument.
-    const ImGuiChildFlags ImGuiChildFlags_SupportedMask_ = ImGuiChildFlags_Border | ImGuiChildFlags_AlwaysUseWindowPadding | ImGuiChildFlags_ResizeX | ImGuiChildFlags_ResizeY;
+    const ImGuiChildFlags ImGuiChildFlags_SupportedMask_ = ImGuiChildFlags_Border | ImGuiChildFlags_AlwaysUseWindowPadding | ImGuiChildFlags_ResizeX | ImGuiChildFlags_ResizeY | ImGuiChildFlags_AutoResizeX | ImGuiChildFlags_AutoResizeY | ImGuiChildFlags_AlwaysAutoResize | ImGuiChildFlags_FrameStyle;
     IM_UNUSED(ImGuiChildFlags_SupportedMask_);
     IM_ASSERT((child_flags & ~ImGuiChildFlags_SupportedMask_) == 0 && "Illegal ImGuiChildFlags value. Did you pass ImGuiWindowFlags values instead of ImGuiChildFlags?");
-    if (window_flags & ImGuiWindowFlags_AlwaysAutoResize)
-        IM_ASSERT((child_flags & (ImGuiChildFlags_ResizeX | ImGuiChildFlags_ResizeY)) == 0 && "Cannot combine ImGuiChildFlags_ResizeX/ImGuiChildFlags_ResizeY with ImGuiWindowFlags_AlwaysAutoResize.");
+    IM_ASSERT((window_flags & ImGuiWindowFlags_AlwaysAutoResize) == 0 && "Cannot specify ImGuiWindowFlags_AlwaysAutoResize for BeginChild(). Use ImGuiChildFlags_AlwaysAutoResize!");
+    if (child_flags & ImGuiChildFlags_AlwaysAutoResize)
+    {
+        IM_ASSERT((child_flags & (ImGuiChildFlags_ResizeX | ImGuiChildFlags_ResizeY)) == 0 && "Cannot use ImGuiChildFlags_ResizeX or ImGuiChildFlags_ResizeY with ImGuiChildFlags_AlwaysAutoResize!");
+        IM_ASSERT((child_flags & (ImGuiChildFlags_AutoResizeX | ImGuiChildFlags_AutoResizeY)) != 0 && "Must use ImGuiChildFlags_AutoResizeX or ImGuiChildFlags_AutoResizeY with ImGuiChildFlags_AlwaysAutoResize!");
+    }
 #ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
     if (window_flags & ImGuiWindowFlags_AlwaysUseWindowPadding)
         child_flags |= ImGuiChildFlags_AlwaysUseWindowPadding;
 #endif
+    if (child_flags & ImGuiChildFlags_AutoResizeX)
+        child_flags &= ~ImGuiChildFlags_ResizeX;
+    if (child_flags & ImGuiChildFlags_AutoResizeY)
+        child_flags &= ~ImGuiChildFlags_ResizeY;
 
+    // Set window flags
     window_flags |= ImGuiWindowFlags_ChildWindow | ImGuiWindowFlags_NoTitleBar | ImGuiWindowFlags_NoDocking;
     window_flags |= (parent_window->Flags & ImGuiWindowFlags_NoMove); // Inherit the NoMove flag
-
+    if (child_flags & (ImGuiChildFlags_AutoResizeX | ImGuiChildFlags_AutoResizeY | ImGuiChildFlags_AlwaysAutoResize))
+        window_flags |= ImGuiWindowFlags_AlwaysAutoResize;
     if ((child_flags & (ImGuiChildFlags_ResizeX | ImGuiChildFlags_ResizeY)) == 0)
         window_flags |= ImGuiWindowFlags_NoResize | ImGuiWindowFlags_NoSavedSettings;
 
+    // Special framed style
+    if (child_flags & ImGuiChildFlags_FrameStyle)
+    {
+        PushStyleColor(ImGuiCol_ChildBg, g.Style.Colors[ImGuiCol_FrameBg]);
+        PushStyleVar(ImGuiStyleVar_ChildRounding, g.Style.FrameRounding);
+        PushStyleVar(ImGuiStyleVar_ChildBorderSize, g.Style.FrameBorderSize);
+        PushStyleVar(ImGuiStyleVar_WindowPadding, g.Style.FramePadding);
+        child_flags |= ImGuiChildFlags_Border | ImGuiChildFlags_AlwaysUseWindowPadding;
+        window_flags |= ImGuiWindowFlags_NoMove;
+    }
+
     // Forward child flags
     g.NextWindowData.Flags |= ImGuiNextWindowDataFlags_HasChildFlags;
     g.NextWindowData.ChildFlags = child_flags;
@@ -5739,12 +5762,9 @@ bool ImGui::BeginChildEx(const char* name, ImGuiID id, const ImVec2& size_arg, I
     // Forward size
     // Important: Begin() has special processing to switch condition to ImGuiCond_FirstUseEver for a given axis when ImGuiChildFlags_ResizeXXX is set.
     // (the alternative would to store conditional flags per axis, which is possible but more code)
-    const ImVec2 content_avail = GetContentRegionAvail();
-    ImVec2 size = ImTrunc(size_arg);
-    if (size.x <= 0.0f)
-        size.x = ImMax(content_avail.x + size.x, 4.0f); // Arbitrary minimum child size (0.0f causing too many issues)
-    if (size.y <= 0.0f)
-        size.y = ImMax(content_avail.y + size.y, 4.0f);
+    const ImVec2 size_avail = GetContentRegionAvail();
+    const ImVec2 size_default((child_flags & ImGuiChildFlags_AutoResizeX) ? 0.0f : size_avail.x, (child_flags & ImGuiChildFlags_AutoResizeY) ? 0.0f : size_avail.y);
+    const ImVec2 size = CalcItemSize(size_arg, size_default.x, size_default.y);
     SetNextWindowSize(size);
 
     // Build up name. If you need to append to a same child from multiple location in the ID stack, use BeginChild(ImGuiID id) with a stable value.
@@ -5756,13 +5776,21 @@ bool ImGui::BeginChildEx(const char* name, ImGuiID id, const ImVec2& size_arg, I
     else
         ImFormatStringToTempBuffer(&temp_window_name, NULL, "%s/%08X", parent_window->Name, id);
 
+    // Set style
     const float backup_border_size = g.Style.ChildBorderSize;
     if ((child_flags & ImGuiChildFlags_Border) == 0)
         g.Style.ChildBorderSize = 0.0f;
 
     // Begin into window
     const bool ret = Begin(temp_window_name, NULL, window_flags);
+
+    // Restore style
     g.Style.ChildBorderSize = backup_border_size;
+    if (child_flags & ImGuiChildFlags_FrameStyle)
+    {
+        PopStyleVar(3);
+        PopStyleColor();
+    }
 
     ImGuiWindow* child_window = g.CurrentWindow;
     child_window->ChildId = id;
@@ -5828,26 +5856,6 @@ void ImGui::EndChild()
     g.LogLinePosY = -FLT_MAX; // To enforce a carriage return
 }
 
-// Helper to create a child window / scrolling region that looks like a normal widget frame.
-bool ImGui::BeginChildFrame(ImGuiID id, const ImVec2& size, ImGuiWindowFlags extra_flags)
-{
-    ImGuiContext& g = *GImGui;
-    const ImGuiStyle& style = g.Style;
-    PushStyleColor(ImGuiCol_ChildBg, style.Colors[ImGuiCol_FrameBg]);
-    PushStyleVar(ImGuiStyleVar_ChildRounding, style.FrameRounding);
-    PushStyleVar(ImGuiStyleVar_ChildBorderSize, style.FrameBorderSize);
-    PushStyleVar(ImGuiStyleVar_WindowPadding, style.FramePadding);
-    bool ret = BeginChild(id, size, ImGuiChildFlags_Border | ImGuiChildFlags_AlwaysUseWindowPadding, ImGuiWindowFlags_NoMove | extra_flags);
-    PopStyleVar(3);
-    PopStyleColor();
-    return ret;
-}
-
-void ImGui::EndChildFrame()
-{
-    EndChild();
-}
-
 static void SetWindowConditionAllowFlags(ImGuiWindow* window, ImGuiCond flags, bool enabled)
 {
     window->SetWindowPosAllowFlags       = enabled ? (window->SetWindowPosAllowFlags       | flags) : (window->SetWindowPosAllowFlags       & ~flags);
@@ -6327,8 +6335,13 @@ static int ImGui::UpdateWindowManualResize(ImGuiWindow* window, const ImVec2& si
             ImVec2 clamp_min(border_n == ImGuiDir_Right ? clamp_rect.Min.x : -FLT_MAX, border_n == ImGuiDir_Down || (border_n == ImGuiDir_Up && window_move_from_title_bar) ? clamp_rect.Min.y : -FLT_MAX);
             ImVec2 clamp_max(border_n == ImGuiDir_Left ? clamp_rect.Max.x : +FLT_MAX, border_n == ImGuiDir_Up ? clamp_rect.Max.y : +FLT_MAX);
             border_target = ImClamp(border_target, clamp_min, clamp_max);
-            if (window->Flags & ImGuiWindowFlags_ChildWindow) // Clamp resizing of childs within parent
-                border_target = ImClamp(border_target, window->ParentWindow->InnerClipRect.Min, window->ParentWindow->InnerClipRect.Max);
+            if (flags & ImGuiWindowFlags_ChildWindow) // Clamp resizing of childs within parent
+            {
+                if ((flags & (ImGuiWindowFlags_HorizontalScrollbar | ImGuiWindowFlags_AlwaysHorizontalScrollbar)) == 0 || (flags & ImGuiWindowFlags_NoScrollbar))
+                    border_target.x = ImClamp(border_target.x, window->ParentWindow->InnerClipRect.Min.x, window->ParentWindow->InnerClipRect.Max.x);
+                if (flags & ImGuiWindowFlags_NoScrollbar)
+                    border_target.y = ImClamp(border_target.y, window->ParentWindow->InnerClipRect.Min.y, window->ParentWindow->InnerClipRect.Max.y);
+            }
             if (!ignore_resize)
                 CalcResizePosSizeFromAnyCorner(window, border_target, ImMin(def.SegmentN1, def.SegmentN2), &pos_target, &size_target);
         }
@@ -7520,7 +7533,12 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
             const bool nav_request = (flags & ImGuiWindowFlags_NavFlattened) && (g.NavAnyRequest && g.NavWindow && g.NavWindow->RootWindowForNav == window->RootWindowForNav);
             if (!g.LogEnabled && !nav_request)
                 if (window->OuterRectClipped.Min.x >= window->OuterRectClipped.Max.x || window->OuterRectClipped.Min.y >= window->OuterRectClipped.Max.y)
-                    window->HiddenFramesCanSkipItems = 1;
+                {
+                    if (window->AutoFitFramesX > 0 || window->AutoFitFramesY > 0)
+                        window->HiddenFramesCannotSkipItems = 1;
+                    else
+                        window->HiddenFramesCanSkipItems = 1;
+                }
 
             // Hide along with parent or if parent is collapsed
             if (parent_window && (parent_window->Collapsed || parent_window->HiddenFramesCanSkipItems > 0))
@@ -8151,10 +8169,14 @@ void ImGui::SetWindowSize(ImGuiWindow* window, const ImVec2& size, ImGuiCond con
     IM_ASSERT(cond == 0 || ImIsPowerOfTwo(cond)); // Make sure the user doesn't attempt to combine multiple condition flags.
     window->SetWindowSizeAllowFlags &= ~(ImGuiCond_Once | ImGuiCond_FirstUseEver | ImGuiCond_Appearing);
 
+    // Enable auto-fit (not done in BeginChild() path unless appearing or combined with ImGuiChildFlags_AlwaysAutoResize)
+    if ((window->Flags & ImGuiWindowFlags_ChildWindow) == 0 || window->Appearing || (window->ChildFlags & ImGuiChildFlags_AlwaysAutoResize) != 0)
+        window->AutoFitFramesX = (size.x <= 0.0f) ? 2 : 0;
+    if ((window->Flags & ImGuiWindowFlags_ChildWindow) == 0 || window->Appearing || (window->ChildFlags & ImGuiChildFlags_AlwaysAutoResize) != 0)
+        window->AutoFitFramesY = (size.y <= 0.0f) ? 2 : 0;
+
     // Set
     ImVec2 old_size = window->SizeFull;
-    window->AutoFitFramesX = (size.x <= 0.0f) ? 2 : 0;
-    window->AutoFitFramesY = (size.y <= 0.0f) ? 2 : 0;
     if (size.x <= 0.0f)
         window->AutoFitOnlyGrows = false;
     else
@@ -9093,6 +9115,13 @@ bool ImGui::IsMouseDoubleClicked(ImGuiMouseButton button)
     return g.IO.MouseClickedCount[button] == 2 && TestKeyOwner(MouseButtonToKey(button), ImGuiKeyOwner_Any);
 }
 
+bool ImGui::IsMouseDoubleClicked(ImGuiMouseButton button, ImGuiID owner_id)
+{
+    ImGuiContext& g = *GImGui;
+    IM_ASSERT(button >= 0 && button < IM_ARRAYSIZE(g.IO.MouseDown));
+    return g.IO.MouseClickedCount[button] == 2 && TestKeyOwner(MouseButtonToKey(button), owner_id);
+}
+
 int ImGui::GetMouseClickedCount(ImGuiMouseButton button)
 {
     ImGuiContext& g = *GImGui;
@@ -12025,7 +12054,7 @@ void ImGui::NavMoveRequestSubmit(ImGuiDir move_dir, ImGuiDir clip_dir, ImGuiNavM
     g.NavMoveFlags = move_flags;
     g.NavMoveScrollFlags = scroll_flags;
     g.NavMoveForwardToNextFrame = false;
-    g.NavMoveKeyMods = g.IO.KeyMods;
+    g.NavMoveKeyMods = (move_flags & ImGuiNavMoveFlags_FocusApi) ? 0 : g.IO.KeyMods;
     g.NavMoveResultLocal.Clear();
     g.NavMoveResultLocalVisible.Clear();
     g.NavMoveResultOther.Clear();
@@ -19946,8 +19975,7 @@ void ImGui::ShowMetricsWindow(bool* p_open)
         Text("KEY OWNERS");
         {
             Indent();
-            if (BeginListBox("##owners", ImVec2(-FLT_MIN, GetTextLineHeightWithSpacing() * 6)))
-            {
+            if (BeginChild("##owners", ImVec2(-FLT_MIN, GetTextLineHeightWithSpacing() * 6), ImGuiChildFlags_FrameStyle | ImGuiChildFlags_ResizeY, ImGuiWindowFlags_NoSavedSettings))
                 for (ImGuiKey key = ImGuiKey_NamedKey_BEGIN; key < ImGuiKey_NamedKey_END; key = (ImGuiKey)(key + 1))
                 {
                     ImGuiKeyOwnerData* owner_data = GetKeyOwnerData(&g, key);
@@ -19957,15 +19985,13 @@ void ImGui::ShowMetricsWindow(bool* p_open)
                         owner_data->LockUntilRelease ? " LockUntilRelease" : owner_data->LockThisFrame ? " LockThisFrame" : "");
                     DebugLocateItemOnHover(owner_data->OwnerCurr);
                 }
-                EndListBox();
-            }
+            EndChild();
             Unindent();
         }
         Text("SHORTCUT ROUTING");
         {
             Indent();
-            if (BeginListBox("##routes", ImVec2(-FLT_MIN, GetTextLineHeightWithSpacing() * 6)))
-            {
+            if (BeginChild("##routes", ImVec2(-FLT_MIN, GetTextLineHeightWithSpacing() * 6), ImGuiChildFlags_FrameStyle | ImGuiChildFlags_ResizeY, ImGuiWindowFlags_NoSavedSettings))
                 for (ImGuiKey key = ImGuiKey_NamedKey_BEGIN; key < ImGuiKey_NamedKey_END; key = (ImGuiKey)(key + 1))
                 {
                     ImGuiKeyRoutingTable* rt = &g.KeysRoutingTable;
@@ -19979,8 +20005,7 @@ void ImGui::ShowMetricsWindow(bool* p_open)
                         idx = routing_data->NextEntryIndex;
                     }
                 }
-                EndListBox();
-            }
+            EndChild();
             Text("(ActiveIdUsing: AllKeyboardKeys: %d, NavDirMask: 0x%X)", g.ActiveIdUsingAllKeyboardKeys, g.ActiveIdUsingNavDirMask);
             Unindent();
         }

imgui.h

@@ -24,7 +24,7 @@
 // Library Version
 // (Integer encoded as XYYZZ for use in #if preprocessor conditionals, e.g. '#if IMGUI_VERSION_NUM >= 12345')
 #define IMGUI_VERSION       "1.90 WIP"
-#define IMGUI_VERSION_NUM   18997
+#define IMGUI_VERSION_NUM   18998
 #define IMGUI_HAS_TABLE
 #define IMGUI_HAS_VIEWPORT          // Viewport WIP branch
 #define IMGUI_HAS_DOCK              // Docking WIP branch
@@ -335,21 +335,26 @@ namespace ImGui
     //   Some information such as 'flags' or 'p_open' will only be considered by the first call to Begin().
     // - Begin() return false to indicate the window is collapsed or fully clipped, so you may early out and omit submitting
     //   anything to the window. Always call a matching End() for each Begin() call, regardless of its return value!
-    //   [Important: due to legacy reason, this is inconsistent with most other functions such as BeginMenu/EndMenu,
-    //    BeginPopup/EndPopup, etc. where the EndXXX call should only be called if the corresponding BeginXXX function
-    //    returned true. Begin and BeginChild are the only odd ones out. Will be fixed in a future update.]
+    //   [Important: due to legacy reason, Begin/End and BeginChild/EndChild are inconsistent with all other functions
+    //    such as BeginMenu/EndMenu, BeginPopup/EndPopup, etc. where the EndXXX call should only be called if the corresponding
+    //    BeginXXX function returned true. Begin and BeginChild are the only odd ones out. Will be fixed in a future update.]
     // - Note that the bottom of window stack always contains a window called "Debug".
     IMGUI_API bool          Begin(const char* name, bool* p_open = NULL, ImGuiWindowFlags flags = 0);
     IMGUI_API void          End();
 
     // Child Windows
     // - Use child windows to begin into a self-contained independent scrolling/clipping regions within a host window. Child windows can embed their own child.
-    // - For each independent axis of 'size': ==0.0f: use remaining host window size / >0.0f: fixed size / <0.0f: use remaining window size minus abs(size) / Each axis can use a different mode, e.g. ImVec2(0,400).
-    // - BeginChild() returns false to indicate the window is collapsed or fully clipped, so you may early out and omit submitting anything to the window.
-    //   Always call a matching EndChild() for each BeginChild() call, regardless of its return value.
-    //   [Important: due to legacy reason, this is inconsistent with most other functions such as BeginMenu/EndMenu,
-    //    BeginPopup/EndPopup, etc. where the EndXXX call should only be called if the corresponding BeginXXX function
-    //    returned true. Begin and BeginChild are the only odd ones out. Will be fixed in a future update.]
+    // - Manual sizing (each axis can use a different setting e.g. ImVec2(0.0f, 400.0f)):
+    //     == 0.0f: use remaining parent window size for this axis.
+    //      > 0.0f: use specified size for this axis.
+    //      < 0.0f: right/bottom-align to specified distance from available content boundaries.
+    // - Specifying ImGuiChildFlags_AutoResizeX or ImGuiChildFlags_AutoResizeY makes the sizing automatic based on child contents.
+    //   Combining both ImGuiChildFlags_AutoResizeX _and_ ImGuiChildFlags_AutoResizeY defeats purpose of a scrolling region and is NOT recommended.
+    // - BeginChild() returns false to indicate the window is collapsed or fully clipped, so you may early out and omit submitting
+    //   anything to the window. Always call a matching EndChild() for each BeginChild() call, regardless of its return value.
+    //   [Important: due to legacy reason, Begin/End and BeginChild/EndChild are inconsistent with all other functions
+    //    such as BeginMenu/EndMenu, BeginPopup/EndPopup, etc. where the EndXXX call should only be called if the corresponding
+    //    BeginXXX function returned true. Begin and BeginChild are the only odd ones out. Will be fixed in a future update.]
     IMGUI_API bool          BeginChild(const char* str_id, const ImVec2& size = ImVec2(0, 0), ImGuiChildFlags child_flags = 0, ImGuiWindowFlags window_flags = 0);
     IMGUI_API bool          BeginChild(ImGuiID id, const ImVec2& size = ImVec2(0, 0), ImGuiChildFlags child_flags = 0, ImGuiWindowFlags window_flags = 0);
     IMGUI_API void          EndChild();
@@ -644,8 +649,8 @@ namespace ImGui
     IMGUI_API bool          Selectable(const char* label, bool* p_selected, ImGuiSelectableFlags flags = 0, const ImVec2& size = ImVec2(0, 0));      // "bool* p_selected" point to the selection state (read-write), as a convenient helper.
 
     // Widgets: List Boxes
-    // - This is essentially a thin wrapper to using BeginChild/EndChild with some stylistic changes.
-    // - The BeginListBox()/EndListBox() api allows you to manage your contents and selection state however you want it, by creating e.g. Selectable() or any items.
+    // - This is essentially a thin wrapper to using BeginChild/EndChild with the ImGuiChildFlags_FrameStyle flag for stylistic changes + displaying a label.
+    // - You can submit contents and manage your selection state however you want it, by creating e.g. Selectable() or any other items.
     // - The simplified/old ListBox() api are helpers over BeginListBox()/EndListBox() which are kept available for convenience purpose. This is analoguous to how Combos are created.
     // - Choose frame width:   size.x > 0.0f: custom  /  size.x < 0.0f or -FLT_MIN: right-align   /  size.x = 0.0f (default): use current ItemWidth
     // - Choose frame height:  size.y > 0.0f: custom  /  size.y < 0.0f or -FLT_MIN: bottom-align  /  size.y = 0.0f (default): arbitrary default height which can fit ~7 items
@@ -925,8 +930,6 @@ namespace ImGui
     IMGUI_API const char*   GetStyleColorName(ImGuiCol idx);                                    // get a string corresponding to the enum value (for display, saving, etc.).
     IMGUI_API void          SetStateStorage(ImGuiStorage* storage);                             // replace current window storage with our own (if you want to manipulate it yourself, typically clear subsection of it)
     IMGUI_API ImGuiStorage* GetStateStorage();
-    IMGUI_API bool          BeginChildFrame(ImGuiID id, const ImVec2& size, ImGuiWindowFlags flags = 0); // helper to create a child window / scrolling region that looks like a normal widget frame
-    IMGUI_API void          EndChildFrame();                                                    // always call EndChildFrame() regardless of BeginChildFrame() return values (which indicates a collapsed/clipped window)
 
     // Text Utilities
     IMGUI_API ImVec2        CalcTextSize(const char* text, const char* text_end = NULL, bool hide_text_after_double_hash = false, float wrap_width = -1.0f);
@@ -1060,6 +1063,13 @@ enum ImGuiWindowFlags_
 
 // Flags for ImGui::BeginChild()
 // (Legacy: bit 0 must always correspond to ImGuiChildFlags_Border to be backward compatible with old API using 'bool border'.
+// About using AutoResizeX/AutoResizeY flags:
+// - May be combined with SetNextWindowSizeConstraints() to set a min/max size for each axis (see "Demo->Child->Auto-resize with Constraints").
+// - Size measurement for a given axis is only performed when the child window is within visible boundaries, or is just appearing.
+//   - This allows BeginChild() to return false when not within boundaries (e.g. when scrolling), which is more optimal. BUT it won't update its auto-size while clipped.
+//     While not perfect, it is a better default behavior as the always-on performance gain is more valuable than the occasional "resizing after becoming visible again" glitch.
+//   - You may also use ImGuiChildFlags_AlwaysAutoResize to force an update even when child window is not in view.
+//     HOWEVER PLEASE UNDERSTAND THAT DOING SO WILL PREVENT BeginChild() FROM EVER RETURNING FALSE, disabling benefits of coarse clipping.
 enum ImGuiChildFlags_
 {
     ImGuiChildFlags_None                    = 0,
@@ -1067,6 +1077,10 @@ enum ImGuiChildFlags_
     ImGuiChildFlags_AlwaysUseWindowPadding  = 1 << 1,   // Pad with style.WindowPadding even if no border are drawn (no padding by default for non-bordered child windows because it makes more sense)
     ImGuiChildFlags_ResizeX                 = 1 << 2,   // Allow resize from right border (layout direction). Enable .ini saving (unless ImGuiWindowFlags_NoSavedSettings passed to window flags)
     ImGuiChildFlags_ResizeY                 = 1 << 3,   // Allow resize from bottom border (layout direction). "
+    ImGuiChildFlags_AutoResizeX             = 1 << 4,   // Enable auto-resizing width. Read "IMPORTANT: Size measurement" details above.
+    ImGuiChildFlags_AutoResizeY             = 1 << 5,   // Enable auto-resizing height. Read "IMPORTANT: Size measurement" details above.
+    ImGuiChildFlags_AlwaysAutoResize        = 1 << 6,   // Combined with AutoResizeX/AutoResizeY. Always measure size even when child is hidden, always return true, always disable clipping optimization! NOT RECOMMENDED.
+    ImGuiChildFlags_FrameStyle              = 1 << 7,   // Style the child window like a framed item: use FrameBg, FrameRounding, FrameBorderSize, FramePadding instead of ChildBg, ChildRounding, ChildBorderSize, WindowPadding.
 };
 
 // Flags for ImGui::InputText()
@@ -2658,9 +2672,9 @@ typedef void (*ImDrawCallback)(const ImDrawList* parent_list, const ImDrawCmd* c
 
 // Special Draw callback value to request renderer backend to reset the graphics/render state.
 // The renderer backend needs to handle this special value, otherwise it will crash trying to call a function at this address.
-// This is useful for example if you submitted callbacks which you know have altered the render state and you want it to be restored.
-// It is not done by default because they are many perfectly useful way of altering render state for imgui contents (e.g. changing shader/blending settings before an Image call).
-#define ImDrawCallback_ResetRenderState     (ImDrawCallback)(-1)
+// This is useful, for example, if you submitted callbacks which you know have altered the render state and you want it to be restored.
+// Render state is not reset by default because they are many perfectly useful way of altering render state (e.g. changing shader/blending settings before an Image call).
+#define ImDrawCallback_ResetRenderState     (ImDrawCallback)(-8)
 
 // Typically, 1 command = 1 GPU draw call (unless command is a callback)
 // - VtxOffset: When 'io.BackendFlags & ImGuiBackendFlags_RendererHasVtxOffset' is enabled,
@@ -3395,6 +3409,8 @@ namespace ImGui
 namespace ImGui
 {
     // OBSOLETED in 1.90.0 (from September 2023)
+    static inline bool  BeginChildFrame(ImGuiID id, const ImVec2& size, ImGuiWindowFlags window_flags = 0)                 { return BeginChild(id, size, ImGuiChildFlags_FrameStyle, window_flags); }
+    static inline void  EndChildFrame()                                                                                    { EndChild(); }
     static inline bool  BeginChild(const char* str_id, const ImVec2& size_arg, bool border, ImGuiWindowFlags window_flags) { return BeginChild(str_id, size_arg, border ? ImGuiChildFlags_Border : ImGuiChildFlags_None, window_flags); }
     static inline bool  BeginChild(ImGuiID id, const ImVec2& size_arg, bool border, ImGuiWindowFlags window_flags)         { return BeginChild(id, size_arg, border ? ImGuiChildFlags_Border : ImGuiChildFlags_None, window_flags);     }
     static inline void  ShowStackToolWindow(bool* p_open = NULL)                            { ShowIDStackToolWindow(p_open); }

imgui_demo.cpp

@@ -1309,6 +1309,9 @@ static void ShowDemoWindowWidgets()
     IMGUI_DEMO_MARKER("Widgets/List Boxes");
     if (ImGui::TreeNode("List boxes"))
     {
+        // BeginListBox() is essentially a thin wrapper to using BeginChild()/EndChild() with the ImGuiChildFlags_FrameStyle flag for stylistic changes + displaying a label.
+        // You may be tempted to simply use BeginChild() directly, however note that BeginChild() requires EndChild() to always be called (inconsistent with BeginListBox()/EndListBox()).
+
         // Using the generic BeginListBox() API, you have full control over how to display the combo contents.
         // (your selection data could be an index, a pointer to the object, an id for the object, a flag intrusively
         // stored in the object itself, etc.)
@@ -2843,10 +2846,27 @@ static void ShowDemoWindowLayout()
         {
             HelpMarker("Drag bottom border to resize. Double-click bottom border to auto-fit to vertical contents.");
             ImGui::PushStyleColor(ImGuiCol_ChildBg, ImGui::GetStyleColorVec4(ImGuiCol_FrameBg));
-            ImGui::BeginChild("ResizableChild", ImVec2(-FLT_MIN, ImGui::GetTextLineHeightWithSpacing() * 8), ImGuiChildFlags_Border | ImGuiChildFlags_ResizeY);
+            if (ImGui::BeginChild("ResizableChild", ImVec2(-FLT_MIN, ImGui::GetTextLineHeightWithSpacing() * 8), ImGuiChildFlags_Border | ImGuiChildFlags_ResizeY))
+                for (int n = 0; n < 10; n++)
+                    ImGui::Text("Line %04d", n);
             ImGui::PopStyleColor();
-            for (int n = 0; n < 10; n++)
-                ImGui::Text("Line %04d", n);
+            ImGui::EndChild();
+        }
+
+        // Child 4: auto-resizing height with a limit
+        ImGui::SeparatorText("Auto-resize with constraints");
+        {
+            static int draw_lines = 3;
+            static int max_height_in_lines = 10;
+            ImGui::SetNextItemWidth(ImGui::GetFontSize() * 8);
+            ImGui::DragInt("Lines Count", &draw_lines, 0.2f);
+            ImGui::SetNextItemWidth(ImGui::GetFontSize() * 8);
+            ImGui::DragInt("Max Height (in Lines)", &max_height_in_lines, 0.2f);
+
+            ImGui::SetNextWindowSizeConstraints(ImVec2(0.0f, ImGui::GetTextLineHeightWithSpacing() * 1), ImVec2(FLT_MAX, ImGui::GetTextLineHeightWithSpacing() * max_height_in_lines));
+            if (ImGui::BeginChild("ConstrainedChild", ImVec2(-FLT_MIN, 0.0f), ImGuiChildFlags_Border | ImGuiChildFlags_AutoResizeY))
+                for (int n = 0; n < draw_lines; n++)
+                    ImGui::Text("Line %04d", n);
             ImGui::EndChild();
         }
 
@@ -2870,6 +2890,10 @@ static void ShowDemoWindowLayout()
             ImGui::CheckboxFlags("ImGuiChildFlags_AlwaysUseWindowPadding", &child_flags, ImGuiChildFlags_AlwaysUseWindowPadding);
             ImGui::CheckboxFlags("ImGuiChildFlags_ResizeX", &child_flags, ImGuiChildFlags_ResizeX);
             ImGui::CheckboxFlags("ImGuiChildFlags_ResizeY", &child_flags, ImGuiChildFlags_ResizeY);
+            ImGui::CheckboxFlags("ImGuiChildFlags_FrameStyle", &child_flags, ImGuiChildFlags_FrameStyle);
+            ImGui::SameLine(); HelpMarker("Style the child window like a framed item: use FrameBg, FrameRounding, FrameBorderSize, FramePadding instead of ChildBg, ChildRounding, ChildBorderSize, WindowPadding.");
+            if (child_flags & ImGuiChildFlags_FrameStyle)
+                override_bg_color = false;
 
             ImGui::SetCursorPosX(ImGui::GetCursorPosX() + (float)offset_x);
             if (override_bg_color)
@@ -5139,6 +5163,7 @@ static void ShowDemoWindowTables()
         ImGui::CheckboxFlags("ImGuiTreeNodeFlags_SpanFullWidth", &tree_node_flags, ImGuiTreeNodeFlags_SpanFullWidth);
         ImGui::CheckboxFlags("ImGuiTreeNodeFlags_SpanAllColumns", &tree_node_flags, ImGuiTreeNodeFlags_SpanAllColumns);
 
+        HelpMarker("See \"Columns flags\" section to configure how indentation is applied to individual columns.");
         if (ImGui::BeginTable("3ways", 3, flags))
         {
             // The first column will use the default _WidthStretch when ScrollX is Off and _WidthFixed when ScrollX is On
@@ -6346,7 +6371,7 @@ void ImGui::ShowAboutWindow(bool* p_open)
 
         bool copy_to_clipboard = ImGui::Button("Copy to clipboard");
         ImVec2 child_size = ImVec2(0, ImGui::GetTextLineHeightWithSpacing() * 18);
-        ImGui::BeginChildFrame(ImGui::GetID("cfg_infos"), child_size, ImGuiWindowFlags_NoMove);
+        ImGui::BeginChild(ImGui::GetID("cfg_infos"), child_size, ImGuiChildFlags_FrameStyle);
         if (copy_to_clipboard)
         {
             ImGui::LogToClipboard();
@@ -6483,7 +6508,7 @@ void ImGui::ShowAboutWindow(bool* p_open)
             ImGui::LogText("\n```\n");
             ImGui::LogFinish();
         }
-        ImGui::EndChildFrame();
+        ImGui::EndChild();
     }
     ImGui::End();
 }
@@ -6695,6 +6720,7 @@ void ImGui::ShowStyleEditor(ImGuiStyle* ref)
                 "Left-click on color square to open color picker,\n"
                 "Right-click to open edit options menu.");
 
+            ImGui::SetNextWindowSizeConstraints(ImVec2(0.0f, ImGui::GetTextLineHeightWithSpacing() * 10), ImVec2(FLT_MAX, FLT_MAX));
             ImGui::BeginChild("##colors", ImVec2(0, 0), ImGuiChildFlags_Border, ImGuiWindowFlags_AlwaysVerticalScrollbar | ImGuiWindowFlags_AlwaysHorizontalScrollbar | ImGuiWindowFlags_NavFlattened);
             ImGui::PushItemWidth(ImGui::GetFontSize() * -12);
             for (int i = 0; i < ImGuiCol_COUNT; i++)
@@ -7518,7 +7544,7 @@ static void ShowExampleAppLayout(bool* p_open)
         // Left
         static int selected = 0;
         {
-            ImGui::BeginChild("left pane", ImVec2(150, 0), ImGuiChildFlags_Border);
+            ImGui::BeginChild("left pane", ImVec2(150, 0), ImGuiChildFlags_Border | ImGuiChildFlags_ResizeX);
             for (int i = 0; i < 100; i++)
             {
                 // FIXME: Good candidate to use ImGuiSelectableFlags_SelectOnNav
@@ -8662,13 +8688,13 @@ void ShowExampleAppDocuments(bool* p_open)
             {
                 ImGui::Text("Save change to the following items?");
                 float item_height = ImGui::GetTextLineHeightWithSpacing();
-                if (ImGui::BeginChildFrame(ImGui::GetID("frame"), ImVec2(-FLT_MIN, 6.25f * item_height)))
+                if (ImGui::BeginChild(ImGui::GetID("frame"), ImVec2(-FLT_MIN, 6.25f * item_height), ImGuiChildFlags_FrameStyle))
                 {
                     for (int n = 0; n < close_queue.Size; n++)
                         if (close_queue[n]->Dirty)
                             ImGui::Text("%s", close_queue[n]->Name);
                 }
-                ImGui::EndChildFrame();
+                ImGui::EndChild();
 
                 ImVec2 button_size(ImGui::GetFontSize() * 7.0f, 0.0f);
                 if (ImGui::Button("Yes", button_size))

imgui_internal.h

@@ -3377,6 +3377,7 @@ namespace ImGui
     IMGUI_API bool              IsMouseDown(ImGuiMouseButton button, ImGuiID owner_id);
     IMGUI_API bool              IsMouseClicked(ImGuiMouseButton button, ImGuiID owner_id, ImGuiInputFlags flags = 0);
     IMGUI_API bool              IsMouseReleased(ImGuiMouseButton button, ImGuiID owner_id);
+    IMGUI_API bool              IsMouseDoubleClicked(ImGuiMouseButton button, ImGuiID owner_id);
 
     // [EXPERIMENTAL] Shortcut Routing
     // - ImGuiKeyChord = a ImGuiKey optionally OR-red with ImGuiMod_Alt/ImGuiMod_Ctrl/ImGuiMod_Shift/ImGuiMod_Super.

imgui_tables.cpp

@@ -321,7 +321,7 @@ bool    ImGui::BeginTableEx(const char* name, ImGuiID id, int columns_count, ImG
     const ImVec2 avail_size = GetContentRegionAvail();
     const ImVec2 actual_outer_size = CalcItemSize(outer_size, ImMax(avail_size.x, 1.0f), use_child_window ? ImMax(avail_size.y, 1.0f) : 0.0f);
     const ImRect outer_rect(outer_window->DC.CursorPos, outer_window->DC.CursorPos + actual_outer_size);
-    const bool outer_window_is_measuring_size = (outer_window->AutoFitFramesX > 0) || (outer_window->AutoFitFramesY > 0); // Doesn't apply to auto-fitting windows!
+    const bool outer_window_is_measuring_size = (outer_window->AutoFitFramesX > 0) || (outer_window->AutoFitFramesY > 0); // Doesn't apply to AlwaysAutoResize windows!
     if (use_child_window && IsClippedEx(outer_rect, 0) && !outer_window_is_measuring_size)
     {
         ItemSize(outer_rect);

imgui_widgets.cpp

@@ -6870,6 +6870,7 @@ void ImGui::SetNextItemSelectionUserData(ImGuiSelectionUserData selection_user_d
 // - ListBox()
 //-------------------------------------------------------------------------
 
+// This is essentially a thin wrapper to using BeginChild/EndChild with the ImGuiChildFlags_FrameStyle flag for stylistic changes + displaying a label.
 // Tip: To have a list filling the entire window width, use size.x = -FLT_MIN and pass an non-visible label e.g. "##empty"
 // Tip: If your vertical size is calculated from an item count (e.g. 10 * item_height) consider adding a fractional part to facilitate seeing scrolling boundaries (e.g. 10.25 * item_height).
 bool ImGui::BeginListBox(const char* label, const ImVec2& size_arg)
@@ -6899,7 +6900,7 @@ bool ImGui::BeginListBox(const char* label, const ImVec2& size_arg)
         return false;
     }
 
-    // FIXME-OPT: We could omit the BeginGroup() if label_size.x but would need to omit the EndGroup() as well.
+    // FIXME-OPT: We could omit the BeginGroup() if label_size.x == 0.0f but would need to omit the EndGroup() as well.
     BeginGroup();
     if (label_size.x > 0.0f)
     {
@@ -6908,7 +6909,7 @@ bool ImGui::BeginListBox(const char* label, const ImVec2& size_arg)
         window->DC.CursorMaxPos = ImMax(window->DC.CursorMaxPos, label_pos + label_size);
     }
 
-    BeginChildFrame(id, frame_bb.GetSize());
+    BeginChild(id, frame_bb.GetSize(), ImGuiChildFlags_FrameStyle);
     return true;
 }
 
@@ -6919,7 +6920,7 @@ void ImGui::EndListBox()
     IM_ASSERT((window->Flags & ImGuiWindowFlags_ChildWindow) && "Mismatched BeginListBox/EndListBox calls. Did you test the return value of BeginListBox?");
     IM_UNUSED(window);
 
-    EndChildFrame();
+    EndChild();
     EndGroup(); // This is only required to be able to do IsItemXXX query on the whole ListBox including label
 }