Merge branch 'master' into viewport

# Conflicts:
#	imgui.cpp
#	imgui_internal.h

CHANGELOG.txt

@@ -41,11 +41,13 @@ VERSION 1.61 WIP
 
 Breaking Changes:
 (IN PROGRESS, WILL ADD TO THIS LIST AS WE WORK ON 1.61)
-- ...
+
+ - Misc: IM_DELETE() helper function added in 1.60 doesn't clear the input _pointer_ reference, more consistent with expectation and allows passing r-value.
 
 Other Changes:
 (IN PROGRESS, WILL ADD TO THIS LIST AS WE WORK ON 1.61)
-- ...
+
+- Settings: Fixed saving an empty .ini file if CreateContext/DestroyContext are called without a single call to NewFrame(). (#1741)
 
 -----------------------------------------------------------------------
 
@@ -199,6 +201,7 @@ Other Changes:
 - Misc: ImVec2: added [] operator. This is becoming desirable for some code working of either axes independently. Better adding it sooner than later.
 - Misc: NewFrame(): Added an assert to detect incorrect filling of the io.KeyMap[] array earlier. (#1555)
 - Misc: Added IM_OFFSETOF() helper in imgui.h (previously was in imgui_internal.h)
+- Misc: Added IM_NEW(), IM_DELETE() helpers in imgui.h (previously were in imgui_internal.h)
 - Misc: Added obsolete redirection function GetItemsLineHeightWithSpacing() (which redirects to GetFrameHeightWithSpacing()), as intended and stated in docs of 1.53.
 - Misc: Added misc/natvis/imgui.natvis for visual studio debugger users to easily visualize imgui internal types. Added to examples projects.
 - Misc: Added IMGUI_USER_CONFIG to define a custom configuration filename. (#255, #1573, #1144, #41)

imgui.cpp

@@ -262,6 +262,7 @@
  Here is a change-log of API breaking changes, if you are using one of the functions listed, expect to have to fix some code.
  Also read releases logs https://github.com/ocornut/imgui/releases for more details.
 
+ - 2018/04/09 (1.61) - IM_DELETE() helper function added in 1.60 doesn't clear the input _pointer_ reference, more consistent with expectation and allows passing r-value.
  - 2018/03/20 (1.60) - Renamed io.WantMoveMouse to io.WantSetMousePos for consistency and ease of understanding (was added in 1.52, _not_ used by core and only honored by some binding ahead of merging the Nav branch).
  - 2018/03/12 (1.60) - Removed ImGuiCol_CloseButton, ImGuiCol_CloseButtonActive, ImGuiCol_CloseButtonHovered as the closing cross uses regular button colors now.
  - 2018/03/08 (1.60) - Changed ImFont::DisplayOffset.y to default to 0 instead of +1. Fixed rounding of Ascent/Descent to match TrueType renderer. If you were adding or subtracting to ImFont::DisplayOffset check if your fonts are correctly aligned vertically.
@@ -739,7 +740,6 @@ static void             SaveIniSettingsToMemory(ImVector<char>& out_buf);
 static void             MarkIniSettingsDirty(ImGuiWindow* window);
 
 static void             ClosePopupToLevel(int remaining);
-static ImGuiWindow*     GetFrontMostModalRootWindow();
 
 static bool             InputTextFilterCharacter(unsigned int* p_char, ImGuiInputTextFlags flags, ImGuiTextEditCallback callback, void* user_data);
 static int              InputTextCalcTextLenAndLineCount(const char* text_begin, const char** out_text_end);
@@ -1928,6 +1928,7 @@ bool ImGuiListClipper::Step()
 //-----------------------------------------------------------------------------
 
 ImGuiWindow::ImGuiWindow(ImGuiContext* context, const char* name)
+    : DrawListInst(&context->DrawListSharedData)
 {
     Name = ImStrdup(name);
     ID = ImHash(name, 0);
@@ -1972,7 +1973,7 @@ ImGuiWindow::ImGuiWindow(ImGuiContext* context, const char* name)
     ItemWidthDefault = 0.0f;
     FontWindowScale = FontDpiScale = 1.0f;
 
-    DrawList = IM_NEW(ImDrawList)(&context->DrawListSharedData);
+    DrawList = &DrawListInst;
     DrawList->_OwnerName = Name;
     ParentWindow = NULL;
     RootWindow = NULL;
@@ -1991,7 +1992,7 @@ ImGuiWindow::ImGuiWindow(ImGuiContext* context, const char* name)
 
 ImGuiWindow::~ImGuiWindow()
 {
-    IM_DELETE(DrawList);
+    IM_ASSERT(DrawList == &DrawListInst);
     IM_DELETE(Name);
     for (int i = 0; i != ColumnsStorage.Size; i++)
         ColumnsStorage[i].~ImGuiColumnsSet();
@@ -3710,7 +3711,7 @@ void ImGui::NewFrameUpdateHoveredWindowAndCaptureFlags()
     IM_ASSERT(g.HoveredWindow == NULL || g.HoveredWindow == g.MovingWindow || g.HoveredWindow->Viewport == g.MousePosViewport);
 
     // Modal windows prevents cursor from hovering behind them.
-    ImGuiWindow* modal_window = GetFrontMostModalRootWindow();
+    ImGuiWindow* modal_window = GetFrontMostPopupModal();
     if (modal_window)
         if (g.HoveredRootWindow && !IsWindowChildOf(g.HoveredRootWindow, modal_window))
             g.HoveredRootWindow = g.HoveredWindow = NULL;
@@ -3882,13 +3883,13 @@ void ImGui::NewFrame()
     g.FramerateSecPerFrameAccum += g.IO.DeltaTime - g.FramerateSecPerFrame[g.FramerateSecPerFrameIdx];
     g.FramerateSecPerFrame[g.FramerateSecPerFrameIdx] = g.IO.DeltaTime;
     g.FramerateSecPerFrameIdx = (g.FramerateSecPerFrameIdx + 1) % IM_ARRAYSIZE(g.FramerateSecPerFrame);
-    g.IO.Framerate = 1.0f / (g.FramerateSecPerFrameAccum / (float)IM_ARRAYSIZE(g.FramerateSecPerFrame));
+    g.IO.Framerate = (g.FramerateSecPerFrameAccum > 0.0f) ? (1.0f / (g.FramerateSecPerFrameAccum / (float)IM_ARRAYSIZE(g.FramerateSecPerFrame))) : FLT_MAX;
 
     // Handle user moving window with mouse (at the beginning of the frame to avoid input lag or sheering)
     NewFrameUpdateMovingWindow();
     NewFrameUpdateHoveredWindowAndCaptureFlags();
     
-    if (GetFrontMostModalRootWindow() != NULL)
+    if (GetFrontMostPopupModal() != NULL)
         g.ModalWindowDarkeningRatio = ImMin(g.ModalWindowDarkeningRatio + g.IO.DeltaTime * 6.0f, 1.0f);
     else
         g.ModalWindowDarkeningRatio = 0.0f;
@@ -4086,12 +4087,15 @@ void ImGui::Shutdown(ImGuiContext* context)
     // The fonts atlas can be used prior to calling NewFrame(), so we clear it even if g.Initialized is FALSE (which would happen if we never called NewFrame)
     if (g.IO.Fonts && g.FontAtlasOwnedByContext)
         IM_DELETE(g.IO.Fonts);
+    g.IO.Fonts = NULL;
 
     // Cleanup of other data are conditional on actually having initialize ImGui.
     if (!g.Initialized)
         return;
 
-    SaveIniSettingsToDisk(g.IO.IniFilename);
+    // Save settings (unless we haven't attempted to load them: CreateContext/DestroyContext without a call to NewFrame shouldn't save an empty file)
+    if (g.SettingsLoaded)
+        SaveIniSettingsToDisk(g.IO.IniFilename);
 
     // Destroy platform windows
     ImGuiContext* backup_context = ImGui::GetCurrentContext();
@@ -4112,8 +4116,6 @@ void ImGui::Shutdown(ImGuiContext* context)
     g.HoveredRootWindow = NULL;
     g.ActiveIdWindow = NULL;
     g.MovingWindow = NULL;
-    for (int i = 0; i < g.SettingsWindows.Size; i++)
-        IM_DELETE(g.SettingsWindows[i].Name);
     g.ColorModifiers.clear();
     g.StyleModifiers.clear();
     g.FontStack.clear();
@@ -4128,6 +4130,8 @@ void ImGui::Shutdown(ImGuiContext* context)
     g.InputTextState.InitialText.clear();
     g.InputTextState.TempTextBuffer.clear();
 
+    for (int i = 0; i < g.SettingsWindows.Size; i++)
+        IM_DELETE(g.SettingsWindows[i].Name);
     g.SettingsWindows.clear();
     g.SettingsHandlers.clear();
 
@@ -4138,6 +4142,7 @@ void ImGui::Shutdown(ImGuiContext* context)
     }
     if (g.LogClipboard)
         IM_DELETE(g.LogClipboard);
+    g.LogClipboard = NULL;
 
     g.Initialized = false;
 }
@@ -4465,7 +4470,7 @@ void ImGui::EndFrame()
                     if (!(g.HoveredWindow->Flags & ImGuiWindowFlags_NoMove) && !(g.HoveredRootWindow->Flags & ImGuiWindowFlags_NoMove))
                         g.MovingWindow = g.HoveredWindow;
                 }
-                else if (g.NavWindow != NULL && GetFrontMostModalRootWindow() == NULL)
+                else if (g.NavWindow != NULL && GetFrontMostPopupModal() == NULL)
                 {
                     // Clicking on void disable focus
                     FocusWindow(NULL);
@@ -4478,7 +4483,7 @@ void ImGui::EndFrame()
             {
                 // Find the top-most window between HoveredWindow and the front most Modal Window.
                 // This is where we can trim the popup stack.
-                ImGuiWindow* modal = GetFrontMostModalRootWindow();
+                ImGuiWindow* modal = GetFrontMostPopupModal();
                 bool hovered_window_above_modal = false;
                 if (modal == NULL)
                     hovered_window_above_modal = true;
@@ -5495,7 +5500,7 @@ void ImGui::ClosePopupsOverWindow(ImGuiWindow* ref_window)
         ClosePopupToLevel(n);
 }
 
-static ImGuiWindow* GetFrontMostModalRootWindow()
+ImGuiWindow* ImGui::GetFrontMostPopupModal()
 {
     ImGuiContext& g = *GImGui;
     for (int n = g.OpenPopupStack.Size-1; n >= 0; n--)
@@ -5818,15 +5823,18 @@ enum ImGuiPopupPositionPolicy
     ImGuiPopupPositionPolicy_ComboBox
 };
 
-static ImVec2 FindBestWindowPosForPopup(ImGuiWindow* window, const ImVec2& ref_pos, const ImVec2& size, ImGuiDir* last_dir, const ImRect& r_avoid, ImGuiPopupPositionPolicy policy = ImGuiPopupPositionPolicy_Default)
+static ImRect FindScreenRectForWindow(ImGuiWindow* window)
+{
+    ImVec2 padding = GImGui->Style.DisplaySafeAreaPadding;
+    ImRect r_screen(ImGui::GetViewportRect(window));
+    r_screen.Expand(ImVec2((window->Size.x - r_screen.GetWidth() > padding.x * 2) ? -padding.x : 0.0f, (window->Size.y - r_screen.GetHeight() > padding.y * 2) ? -padding.y : 0.0f));
+    return r_screen;
+}
+    
+// r_avoid = the rectangle to avoid (e.g. for tooltip it is a rectangle around the mouse cursor which we want to avoid. for popups it's a small point around the cursor.)
+// r_outer = the visible area rectangle, minus safe area padding. If our popup size won't fit because of safe area padding we ignore it.
+static ImVec2 FindBestWindowPosForPopupEx(const ImVec2& ref_pos, const ImVec2& size, ImGuiDir* last_dir, const ImRect& r_outer, const ImRect& r_avoid, ImGuiPopupPositionPolicy policy = ImGuiPopupPositionPolicy_Default)
 {
-    const ImGuiStyle& style = GImGui->Style;
-
-    // r_avoid = the rectangle to avoid (e.g. for tooltip it is a rectangle around the mouse cursor which we want to avoid. for popups it's a small point around the cursor.)
-    // r_outer = the visible area rectangle, minus safe area padding. If our popup size won't fit because of safe area padding we ignore it.
-    ImVec2 safe_padding = style.DisplaySafeAreaPadding;
-    ImRect r_outer(ImGui::GetViewportRect(window));
-    r_outer.Expand(ImVec2((size.x - r_outer.GetWidth() > safe_padding.x*2) ? -safe_padding.x : 0.0f, (size.y - r_outer.GetHeight() > safe_padding.y*2) ? -safe_padding.y : 0.0f));
     ImVec2 base_pos_clamped = ImClamp(ref_pos, r_outer.Min, r_outer.Max - size);
     //GImGui->OverlayDrawList.AddRect(r_avoid.Min, r_avoid.Max, IM_COL32(255,0,0,255));
     //GImGui->OverlayDrawList.AddRect(r_outer.Min, r_outer.Max, IM_COL32(0,255,0,255));
@@ -5878,6 +5886,49 @@ static ImVec2 FindBestWindowPosForPopup(ImGuiWindow* window, const ImVec2& ref_p
     return pos;
 }
 
+static ImVec2 FindBestWindowPosForPopup(ImGuiWindow* window)
+{
+    ImGuiContext& g = *GImGui;
+
+    ImRect r_screen = FindScreenRectForWindow(window);
+    if (window->Flags & ImGuiWindowFlags_ChildMenu)
+    {
+        // Child menus typically request _any_ position within the parent menu item, and then our FindBestPopupWindowPos() function will move the new menu outside the parent bounds.
+        // This is how we end up with child menus appearing (most-commonly) on the right of the parent menu.
+        IM_ASSERT(g.CurrentWindow == window);
+        ImGuiWindow* parent_menu = g.CurrentWindowStack[g.CurrentWindowStack.Size - 2];
+        float horizontal_overlap = g.Style.ItemSpacing.x;       // We want some overlap to convey the relative depth of each menu (currently the amount of overlap is hard-coded to style.ItemSpacing.x).
+        ImRect r_avoid;
+        if (parent_menu->DC.MenuBarAppending)
+            r_avoid = ImRect(-FLT_MAX, parent_menu->Pos.y + parent_menu->TitleBarHeight(), FLT_MAX, parent_menu->Pos.y + parent_menu->TitleBarHeight() + parent_menu->MenuBarHeight());
+        else
+            r_avoid = ImRect(parent_menu->Pos.x + horizontal_overlap, -FLT_MAX, parent_menu->Pos.x + parent_menu->Size.x - horizontal_overlap - parent_menu->ScrollbarSizes.x, FLT_MAX);
+        return FindBestWindowPosForPopupEx(window->PosFloat, window->Size, &window->AutoPosLastDirection, r_screen, r_avoid);
+    }
+    if (window->Flags & ImGuiWindowFlags_Popup)
+    {
+        ImRect r_avoid(window->PosFloat.x - 1, window->PosFloat.y - 1, window->PosFloat.x + 1, window->PosFloat.y + 1);
+        return FindBestWindowPosForPopupEx(window->PosFloat, window->Size, &window->AutoPosLastDirection, r_screen, r_avoid);
+    }
+    if (window->Flags & ImGuiWindowFlags_Tooltip)
+    {
+        // Position tooltip (always follows mouse)
+        float sc = g.Style.MouseCursorScale;
+        ImVec2 ref_pos = (!g.NavDisableHighlight && g.NavDisableMouseHover) ? NavCalcPreferredMousePos() : g.IO.MousePos;
+        ImRect r_avoid;
+        if (!g.NavDisableHighlight && g.NavDisableMouseHover && !(g.IO.ConfigFlags & ImGuiConfigFlags_NavEnableSetMousePos))
+            r_avoid = ImRect(ref_pos.x - 16, ref_pos.y - 8, ref_pos.x + 16, ref_pos.y + 8);
+        else
+            r_avoid = ImRect(ref_pos.x - 16, ref_pos.y - 8, ref_pos.x + 24 * sc, ref_pos.y + 24 * sc); // FIXME: Hard-coded based on mouse cursor shape expectation. Exact dimension not very important.
+        ImVec2 pos = FindBestWindowPosForPopupEx(ref_pos, window->Size, &window->AutoPosLastDirection, r_screen, r_avoid);
+        if (window->AutoPosLastDirection == ImGuiDir_None)
+            pos = ref_pos + ImVec2(2, 2); // If there's not enough room, for tooltip we prefer avoiding the cursor at all cost even if it means that part of the tooltip won't be visible.
+        return pos;
+    }
+    IM_ASSERT(0);
+    return window->Pos;
+}
+
 static void SetWindowConditionAllowFlags(ImGuiWindow* window, ImGuiCond flags, bool enabled)
 {
     window->SetWindowPosAllowFlags       = enabled ? (window->SetWindowPosAllowFlags       | flags) : (window->SetWindowPosAllowFlags       & ~flags);
@@ -6191,9 +6242,9 @@ static void ImGui::UpdateSelectWindowViewport(ImGuiWindow* window)
 
 struct ImGuiResizeGripDef
 {
-    ImVec2           CornerPos;
-    ImVec2           InnerDir;
-    int              AngleMin12, AngleMax12;
+    ImVec2  CornerPos;
+    ImVec2  InnerDir;
+    int     AngleMin12, AngleMax12;
 };
 
 const ImGuiResizeGripDef resize_grip_def[4] =
@@ -6598,44 +6649,13 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
 
         const bool window_pos_with_pivot = (window->SetWindowPosVal.x != FLT_MAX && window->HiddenFrames == 0);
         if (window_pos_with_pivot)
-        {
-            // Position given a pivot (e.g. for centering)
-            SetWindowPos(window, ImMax(style.DisplaySafeAreaPadding, window->SetWindowPosVal - window->SizeFull * window->SetWindowPosPivot), 0);
-        }
-        else if (flags & ImGuiWindowFlags_ChildMenu)
-        {
-            // Child menus typically request _any_ position within the parent menu item, and then our FindBestPopupWindowPos() function will move the new menu outside the parent bounds.
-            // This is how we end up with child menus appearing (most-commonly) on the right of the parent menu.
-            IM_ASSERT(window_pos_set_by_api);
-            float horizontal_overlap = style.ItemSpacing.x; // We want some overlap to convey the relative depth of each popup (currently the amount of overlap it is hard-coded to style.ItemSpacing.x, may need to introduce another style value).
-            ImGuiWindow* parent_menu = parent_window_in_stack;
-            ImRect rect_to_avoid;
-            if (parent_menu->DC.MenuBarAppending)
-                rect_to_avoid = ImRect(-FLT_MAX, parent_menu->Pos.y + parent_menu->TitleBarHeight(), FLT_MAX, parent_menu->Pos.y + parent_menu->TitleBarHeight() + parent_menu->MenuBarHeight());
-            else
-                rect_to_avoid = ImRect(parent_menu->Pos.x + horizontal_overlap, -FLT_MAX, parent_menu->Pos.x + parent_menu->Size.x - horizontal_overlap - parent_menu->ScrollbarSizes.x, FLT_MAX);
-            window->PosFloat = FindBestWindowPosForPopup(window, window->PosFloat, window->Size, &window->AutoPosLastDirection, rect_to_avoid);
-        }
+            SetWindowPos(window, ImMax(style.DisplaySafeAreaPadding, window->SetWindowPosVal - window->SizeFull * window->SetWindowPosPivot), 0); // Position given a pivot (e.g. for centering)
+        else if ((flags & ImGuiWindowFlags_ChildMenu) != 0)
+            window->PosFloat = FindBestWindowPosForPopup(window);
         else if ((flags & ImGuiWindowFlags_Popup) != 0 && !window_pos_set_by_api && window_just_appearing_after_hidden_for_resize)
-        {
-            ImRect rect_to_avoid(window->PosFloat.x - 1, window->PosFloat.y - 1, window->PosFloat.x + 1, window->PosFloat.y + 1);
-            window->PosFloat = FindBestWindowPosForPopup(window, window->PosFloat, window->Size, &window->AutoPosLastDirection, rect_to_avoid);
-        }
-
-        // Position tooltip (always follows mouse)
-        if ((flags & ImGuiWindowFlags_Tooltip) != 0 && !window_pos_set_by_api && !window_is_child_tooltip)
-        {
-            float sc = g.Style.MouseCursorScale;
-            ImVec2 ref_pos = (!g.NavDisableHighlight && g.NavDisableMouseHover) ? NavCalcPreferredMousePos() : g.IO.MousePos;
-            ImRect rect_to_avoid;
-            if (!g.NavDisableHighlight && g.NavDisableMouseHover && !(g.IO.ConfigFlags & ImGuiConfigFlags_NavEnableSetMousePos))
-                rect_to_avoid = ImRect(ref_pos.x - 16, ref_pos.y - 8, ref_pos.x + 16, ref_pos.y + 8); 
-            else
-                rect_to_avoid = ImRect(ref_pos.x - 16, ref_pos.y - 8, ref_pos.x + 24 * sc, ref_pos.y + 24 * sc); // FIXME: Hard-coded based on mouse cursor shape expectation. Exact dimension not very important.
-            window->PosFloat = FindBestWindowPosForPopup(window, ref_pos, window->Size, &window->AutoPosLastDirection, rect_to_avoid);
-            if (window->AutoPosLastDirection == ImGuiDir_None)
-                window->PosFloat = ref_pos + ImVec2(2,2); // If there's not enough room, for tooltip we prefer avoiding the cursor at all cost even if it means that part of the tooltip won't be visible.
-        }
+            window->PosFloat = FindBestWindowPosForPopup(window);
+        else if ((flags & ImGuiWindowFlags_Tooltip) != 0 && !window_pos_set_by_api && !window_is_child_tooltip)
+            window->PosFloat = FindBestWindowPosForPopup(window);
 
         // Clamp position so window stays visible within its viewport
         ImRect viewport_rect(GetViewportRect(window));
@@ -6702,7 +6722,7 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
             PushClipRect(viewport_rect.Min, viewport_rect.Max, true);
 
         // Draw modal window background (darkens what is behind them, all viewports)
-        if ((flags & ImGuiWindowFlags_Modal) != 0 && window == GetFrontMostModalRootWindow() && window->HiddenFrames <= 0)
+        if ((flags & ImGuiWindowFlags_Modal) != 0 && window == GetFrontMostPopupModal() && window->HiddenFrames <= 0)
             for (int viewport_n = 0; viewport_n < g.Viewports.Size; viewport_n++)
             {
                 ImGuiViewportP* viewport = g.Viewports[viewport_n];
@@ -11516,7 +11536,8 @@ bool ImGui::BeginCombo(const char* label, const char* preview_value, ImGuiComboF
             ImVec2 size_expected = CalcSizeAfterConstraint(popup_window, CalcSizeAutoFit(popup_window, size_contents));
             if (flags & ImGuiComboFlags_PopupAlignLeft)
                 popup_window->AutoPosLastDirection = ImGuiDir_Left;
-            ImVec2 pos = FindBestWindowPosForPopup(popup_window, frame_bb.GetBL(), size_expected, &popup_window->AutoPosLastDirection, frame_bb, ImGuiPopupPositionPolicy_ComboBox);
+            ImRect r_outer = FindScreenRectForWindow(popup_window);
+            ImVec2 pos = FindBestWindowPosForPopupEx(frame_bb.GetBL(), size_expected, &popup_window->AutoPosLastDirection, r_outer, frame_bb, ImGuiPopupPositionPolicy_ComboBox);
             SetNextWindowPos(pos);
         }
 

imgui.h

@@ -1236,7 +1236,7 @@ inline void* operator new(size_t, ImNewDummy, void* ptr) { return ptr; }
 inline void  operator delete(void*, ImNewDummy, void*)   {} // This is only required so we can use the symetrical new()
 #define IM_PLACEMENT_NEW(_PTR)              new(ImNewDummy(), _PTR)
 #define IM_NEW(_TYPE)                       new(ImNewDummy(), ImGui::MemAlloc(sizeof(_TYPE))) _TYPE
-template<typename T> void IM_DELETE(T*& p)  { if (p) { p->~T(); ImGui::MemFree(p); p = NULL; } }
+template<typename T> void IM_DELETE(T* p)   { if (p) { p->~T(); ImGui::MemFree(p); } }
 
 // Helper: Execute a block of code at maximum once a frame. Convenient if you want to quickly create an UI within deep-nested code that runs multiple times every frame.
 // Usage: static ImGuiOnceUponAFrame oaf; if (oaf) ImGui::Text("This will be called only once per frame");

imgui_draw.cpp

@@ -1733,7 +1733,7 @@ bool    ImFontAtlasBuildWithStbTruetype(ImFontAtlas* atlas)
         IM_ASSERT(cfg.DstFont && (!cfg.DstFont->IsLoaded() || cfg.DstFont->ContainerAtlas == atlas));
 
         const int font_offset = stbtt_GetFontOffsetForIndex((unsigned char*)cfg.FontData, cfg.FontNo);
-        IM_ASSERT(font_offset >= 0);
+        IM_ASSERT(font_offset >= 0 && "FontData is incorrect, or FontNo cannot be found.");
         if (!stbtt_InitFont(&tmp.FontInfo, (unsigned char*)cfg.FontData, font_offset))
         {
             atlas->TexWidth = atlas->TexHeight = 0; // Reset output on failure

imgui_internal.h

@@ -991,7 +991,8 @@ struct IMGUI_API ImGuiWindow
     ImVector<ImGuiColumnsSet> ColumnsStorage;
     float                   FontWindowScale;                    // User scale multiplier per-window
     float                   FontDpiScale;
-    ImDrawList*             DrawList;
+    ImDrawList*             DrawList;                           // == &DrawListInst (for backward compatibility reason with code using imgui_internal.h we keep this a pointer)
+    ImDrawList              DrawListInst;
     ImGuiWindow*            ParentWindow;                       // If we are a child _or_ popup window, this is pointing to our parent. Otherwise NULL.
     ImGuiWindow*            RootWindow;                         // Point to ourself or first ancestor that is not a child window.
     ImGuiWindow*            RootWindowForTitleBarHighlight;     // Point to ourself or first ancestor which will display TitleBgActive color when this window is active.
@@ -1109,6 +1110,7 @@ namespace ImGui
     IMGUI_API bool          IsPopupOpen(ImGuiID id);
     IMGUI_API bool          BeginPopupEx(ImGuiID id, ImGuiWindowFlags extra_flags);
     IMGUI_API void          BeginTooltipEx(ImGuiWindowFlags extra_flags, bool override_previous_tooltip = true);
+    IMGUI_API ImGuiWindow*  GetFrontMostPopupModal();
 
     IMGUI_API void          NavInitWindow(ImGuiWindow* window, bool force_reinit);
     IMGUI_API void          NavMoveRequestCancel();