Columns: Fix for explicit content width and scrollbar. (#519, #125)

imgui.cpp

@@ -10050,10 +10050,10 @@ void ImGui::BeginColumns(const char* id, int columns_count, ImGuiColumnsFlags fl
     window->DC.ColumnsCount = columns_count;
     window->DC.ColumnsFlags = flags;
 
-    const float content_region_width = (window->SizeContentsExplicit.x != 0.0f) ? window->SizeContentsExplicit.x : window->Size.x;
+    const float content_region_width = (window->SizeContentsExplicit.x != 0.0f) ? (window->SizeContentsExplicit.x) : (window->Size.x -window->ScrollbarSizes.x);
     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.ColumnsMaxX = content_region_width - window->Scroll.x - window->ScrollbarSizes.x;
+    window->DC.ColumnsMaxX = content_region_width - window->Scroll.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;

imgui_demo.cpp

@@ -1623,13 +1623,13 @@ void ImGui::ShowTestWindow(bool* p_open)
 
         if (ImGui::TreeNode("Horizontal Scrolling"))
         {
-            ImGui::SetNextWindowContentWidth(2000);
+            ImGui::SetNextWindowContentWidth(1500);
             ImGui::BeginChild("##scrollingregion", ImVec2(0, 120), false, ImGuiWindowFlags_HorizontalScrollbar);
             ImGui::Columns(10);
             for (int i = 0; i < 20; i++)
                 for (int j = 0; j < 10; j++)
                 {
-                    ImGui::Text("Line %d Column %d", i, j);
+                    ImGui::Text("Line %d Column %d...", i, j);
                     ImGui::NextColumn();
                 }
             ImGui::Columns(1);