Columns: Extent stop at the right-most clipped pixel. The right-most column might appear a little wider but it's usable space matches the others. (#125). +9 Internal: Store InnerClipRect.

imgui.cpp

@@ -6131,21 +6131,20 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
         window->InnerRect.Max.y = window->Pos.y + window->Size.y - window->ScrollbarSizes.y - window->WindowBorderSize;
         //window->DrawList->AddRect(window->InnerRect.Min, window->InnerRect.Max, IM_COL32_WHITE);
 
+        // Inner clipping rectangle
+        // Force round operator last to ensure that e.g. (int)(max.x-min.x) in user's render code produce correct result.
+        window->InnerClipRect.Min.x = ImFloor(0.5f + window->InnerRect.Min.x + ImMax(0.0f, ImFloor(window->WindowPadding.x*0.5f - window->WindowBorderSize)));
+        window->InnerClipRect.Min.y = ImFloor(0.5f + window->InnerRect.Min.y);
+        window->InnerClipRect.Max.x = ImFloor(0.5f + window->InnerRect.Max.x - ImMax(0.0f, ImFloor(window->WindowPadding.x*0.5f - window->WindowBorderSize)));
+        window->InnerClipRect.Max.y = ImFloor(0.5f + window->InnerRect.Max.y);
+
         // After Begin() we fill the last item / hovered data using the title bar data. Make that a standard behavior (to allow usage of context menus on title bar only, etc.).
         window->DC.LastItemId = window->MoveId;
         window->DC.LastItemStatusFlags = IsMouseHoveringRect(title_bar_rect.Min, title_bar_rect.Max, false) ? ImGuiItemStatusFlags_HoveredRect : 0;
         window->DC.LastItemRect = title_bar_rect;
     }
 
-    // Inner clipping rectangle
-    // Force round operator last to ensure that e.g. (int)(max.x-min.x) in user's render code produce correct result.
-    const float border_size = window->WindowBorderSize;
-    ImRect clip_rect;
-    clip_rect.Min.x = ImFloor(0.5f + window->InnerRect.Min.x + ImMax(0.0f, ImFloor(window->WindowPadding.x*0.5f - border_size)));
-    clip_rect.Min.y = ImFloor(0.5f + window->InnerRect.Min.y);
-    clip_rect.Max.x = ImFloor(0.5f + window->InnerRect.Max.x - ImMax(0.0f, ImFloor(window->WindowPadding.x*0.5f - border_size)));
-    clip_rect.Max.y = ImFloor(0.5f + window->InnerRect.Max.y);
-    PushClipRect(clip_rect.Min, clip_rect.Max, true);
+    PushClipRect(window->InnerClipRect.Min, window->InnerClipRect.Max, true);
 
     // Clear 'accessed' flag last thing (After PushClipRect which will set the flag. We want the flag to stay false when the default "Debug" window is unused)
     if (first_begin_of_the_frame)
@@ -12512,7 +12511,7 @@ void ImGui::BeginColumns(const char* str_id, int columns_count, ImGuiColumnsFlag
     window->DC.ColumnsSet = columns;
 
     // Set state for first column
-    const float content_region_width = (window->SizeContentsExplicit.x != 0.0f) ? (window->SizeContentsExplicit.x) : (window->Size.x -window->ScrollbarSizes.x);
+    const float content_region_width = (window->SizeContentsExplicit.x != 0.0f) ? (window->SizeContentsExplicit.x) : (window->InnerClipRect.Max.x - window->Pos.x);
     columns->MinX = window->DC.IndentX - g.Style.ItemSpacing.x; // Lock our horizontal range
     columns->MaxX = ImMax(content_region_width - window->Scroll.x, columns->MinX + 1.0f);
     columns->StartPosY = window->DC.CursorPos.y;

imgui_internal.h

@@ -944,7 +944,7 @@ struct IMGUI_API ImGuiWindow
     ImVector<ImGuiID>       IDStack;                            // ID stack. ID are hashes seeded with the value at the top of the stack
     ImRect                  ClipRect;                           // = DrawList->clip_rect_stack.back(). Scissoring / clipping rectangle. x1, y1, x2, y2.
     ImRect                  WindowRectClipped;                  // = WindowRect just after setup in Begin(). == window->Rect() for root window.
-    ImRect                  InnerRect;
+    ImRect                  InnerRect, InnerClipRect;
     int                     LastFrameActive;
     float                   ItemWidthDefault;
     ImGuiMenuColumns        MenuColumns;                        // Simplified columns storage for menu items