Scrollbar: Fix ScrollbarX enable test subtracting WindowPadding.x. This has been here since 65a191c005 (#246) tho at the time it is possible that SizeContents wasn't calculated as evenly.

Test: auto-resize with: ImGui::Begin("Test", NULL, ImGuiWindowFlags_HorizontalScrollbar); ImGui::Button("##xxx", ImVec2(500,500)); ImGui::End();

imgui.cpp

@@ -4670,7 +4670,7 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
             float size_x_for_scrollbars = size_full_modified.x != FLT_MAX ? window->SizeFull.x : window->SizeFullAtLastBegin.x;
             float size_y_for_scrollbars = size_full_modified.y != FLT_MAX ? window->SizeFull.y : window->SizeFullAtLastBegin.y;
             window->ScrollbarY = (flags & ImGuiWindowFlags_AlwaysVerticalScrollbar) || ((window->SizeContents.y > size_y_for_scrollbars) && !(flags & ImGuiWindowFlags_NoScrollbar));
-            window->ScrollbarX = (flags & ImGuiWindowFlags_AlwaysHorizontalScrollbar) || ((window->SizeContents.x > size_x_for_scrollbars - (window->ScrollbarY ? style.ScrollbarSize : 0.0f) - window->WindowPadding.x) && !(flags & ImGuiWindowFlags_NoScrollbar) && (flags & ImGuiWindowFlags_HorizontalScrollbar));
+            window->ScrollbarX = (flags & ImGuiWindowFlags_AlwaysHorizontalScrollbar) || ((window->SizeContents.x > size_x_for_scrollbars - (window->ScrollbarY ? style.ScrollbarSize : 0.0f)) && !(flags & ImGuiWindowFlags_NoScrollbar) && (flags & ImGuiWindowFlags_HorizontalScrollbar));
             if (window->ScrollbarX && !window->ScrollbarY)
                 window->ScrollbarY = (window->SizeContents.y > size_y_for_scrollbars + style.ScrollbarSize) && !(flags & ImGuiWindowFlags_NoScrollbar);
             window->ScrollbarSizes = ImVec2(window->ScrollbarY ? style.ScrollbarSize : 0.0f, window->ScrollbarX ? style.ScrollbarSize : 0.0f);