Columns: A set of column (and most importantly the right-most column) do not register its content to the parent, not affecting the window contents size. (#519, #125, #913)

imgui.cpp

@@ -4345,6 +4345,7 @@ bool ImGui::Begin(const char* name, bool* p_open, const ImVec2& size_on_first_us
         window->DC.ColumnsCurrent = 0;
         window->DC.ColumnsCount = 1;
         window->DC.ColumnsStartPosY = window->DC.CursorPos.y;
+        window->DC.ColumnsStartMaxPosX = window->DC.CursorMaxPos.x;
         window->DC.ColumnsCellMinY = window->DC.ColumnsCellMaxY = window->DC.ColumnsStartPosY;
         window->DC.TreeDepth = 0;
         window->DC.StateStorage = &window->StateStorage;
@@ -10051,6 +10052,7 @@ void ImGui::BeginColumns(const char* id, int columns_count, ImGuiColumnsFlags fl
     window->DC.ColumnsMinX = window->DC.IndentX - g.Style.ItemSpacing.x; // Lock our horizontal range
     window->DC.ColumnsMaxX = content_region_width - window->Scroll.x - ((window->Flags & ImGuiWindowFlags_NoScrollbar) ? 0 : g.Style.ScrollbarSize);// - window->WindowPadding().x;
     window->DC.ColumnsStartPosY = window->DC.CursorPos.y;
+    window->DC.ColumnsStartMaxPosX = window->DC.CursorMaxPos.x;
     window->DC.ColumnsCellMinY = window->DC.ColumnsCellMaxY = window->DC.CursorPos.y;
     window->DC.ColumnsOffsetX = 0.0f;
     window->DC.CursorPos.x = (float)(int)(window->Pos.x + window->DC.IndentX + window->DC.ColumnsOffsetX);
@@ -10084,6 +10086,7 @@ void ImGui::EndColumns()
 
 	window->DC.ColumnsCellMaxY = ImMax(window->DC.ColumnsCellMaxY, window->DC.CursorPos.y);
 	window->DC.CursorPos.y = window->DC.ColumnsCellMaxY;
+    window->DC.CursorMaxPos.x = ImMax(window->DC.ColumnsStartMaxPosX, window->DC.ColumnsMaxX);  // Columns don't grow parent
 
 	// Draw columns borders and handle resize
 	if (!(window->DC.ColumnsFlags & ImGuiColumnsFlags_NoBorder) && !window->SkipItems)

imgui_internal.h

@@ -605,6 +605,7 @@ struct IMGUI_API ImGuiDrawContext
     float                   ColumnsMinX;
     float                   ColumnsMaxX;
     float                   ColumnsStartPosY;
+    float                   ColumnsStartMaxPosX;   // Backup of CursorMaxPos
     float                   ColumnsCellMinY;
     float                   ColumnsCellMaxY;
     ImGuiColumnsFlags       ColumnsFlags;
@@ -638,6 +639,7 @@ struct IMGUI_API ImGuiDrawContext
         ColumnsCount = 1;
         ColumnsMinX = ColumnsMaxX = 0.0f;
         ColumnsStartPosY = 0.0f;
+        ColumnsStartMaxPosX = 0.0f;
         ColumnsCellMinY = ColumnsCellMaxY = 0.0f;
         ColumnsFlags = 0;
         ColumnsSetId = 0;