Refine editor tree alignment and project panel events

new_editor/include/XCEditor/Collections/UIEditorTreeView.h

@@ -43,6 +43,7 @@ struct UIEditorTreeViewMetrics {
     float disclosureLabelGap = 6.0f;
     float iconExtent = 18.0f;
     float iconLabelGap = 2.0f;
+    float iconInsetY = 0.0f;
     float labelInsetY = 6.0f;
     float cornerRounding = 6.0f;
     float borderThickness = 1.0f;