Style: close button and collapse/window-menu button hover highlight made rectangular instead of round.

The reason they were round in the first place was to work better with rounded windows/frames.
However since the 4a8142449 rework #6749 we can naturally use a tigher bounding box and it seems to work ok either way.

docs/CHANGELOG.txt

@@ -77,6 +77,7 @@ Other changes:
     Disabling this was previously possible for Selectable() via a direct flag but not for MenuItem().
     (#1379, #1468, #2200, #4936, #5216, #7302, #7573)
   - This was mostly all previously in imgui_internal.h.
+- Style: close button and collapse/window-menu button hover highlight made rectangular instead of round.
 - Debug Tools: Added IMGUI_DEBUG_LOG(), ImGui::DebugLog() in public API. (#5855)
   Debug log entries add a imgui frame counter prefix + are redirected to ShowDebugLogWindow() and
   other configurable locations. Always call IMGUI_DEBUG_LOG() for maximum stripping in caller code.

imgui_widgets.cpp

@@ -835,17 +835,15 @@ bool ImGui::CloseButton(ImGuiID id, const ImVec2& pos)
         return pressed;
 
     // Render
-    // FIXME: Clarify this mess
-    ImU32 col = GetColorU32(held ? ImGuiCol_ButtonActive : ImGuiCol_ButtonHovered);
-    ImVec2 center = bb.GetCenter();
+    ImU32 bg_col = GetColorU32(held ? ImGuiCol_ButtonActive : ImGuiCol_ButtonHovered);
     if (hovered)
-        window->DrawList->AddCircleFilled(center, ImMax(2.0f, g.FontSize * 0.5f + 1.0f), col);
-
-    float cross_extent = g.FontSize * 0.5f * 0.7071f - 1.0f;
+        window->DrawList->AddRectFilled(bb.Min, bb.Max, bg_col);
+    RenderNavHighlight(bb, id, ImGuiNavHighlightFlags_Compact);
     ImU32 cross_col = GetColorU32(ImGuiCol_Text);
-    center -= ImVec2(0.5f, 0.5f);
-    window->DrawList->AddLine(center + ImVec2(+cross_extent, +cross_extent), center + ImVec2(-cross_extent, -cross_extent), cross_col, 1.0f);
-    window->DrawList->AddLine(center + ImVec2(+cross_extent, -cross_extent), center + ImVec2(-cross_extent, +cross_extent), cross_col, 1.0f);
+    ImVec2 cross_center = bb.GetCenter() - ImVec2(0.5f, 0.5f);
+    float cross_extent = g.FontSize * 0.5f * 0.7071f - 1.0f;
+    window->DrawList->AddLine(cross_center + ImVec2(+cross_extent, +cross_extent), cross_center + ImVec2(-cross_extent, -cross_extent), cross_col, 1.0f);
+    window->DrawList->AddLine(cross_center + ImVec2(+cross_extent, -cross_extent), cross_center + ImVec2(-cross_extent, +cross_extent), cross_col, 1.0f);
 
     return pressed;
 }
@@ -866,7 +864,8 @@ bool ImGui::CollapseButton(ImGuiID id, const ImVec2& pos)
     ImU32 bg_col = GetColorU32((held && hovered) ? ImGuiCol_ButtonActive : hovered ? ImGuiCol_ButtonHovered : ImGuiCol_Button);
     ImU32 text_col = GetColorU32(ImGuiCol_Text);
     if (hovered || held)
-        window->DrawList->AddCircleFilled(bb.GetCenter() + ImVec2(0.0f, -0.5f), g.FontSize * 0.5f + 1.0f, bg_col);
+        window->DrawList->AddRectFilled(bb.Min, bb.Max, bg_col);
+    RenderNavHighlight(bb, id, ImGuiNavHighlightFlags_Compact);
     RenderArrow(window->DrawList, bb.Min, text_col, window->Collapsed ? ImGuiDir_Right : ImGuiDir_Down, 1.0f);
 
     // Switch to moving the window after mouse is moved beyond the initial drag threshold