Fast expand/collapse with mouse is being recognized as double-click and trigger some selection-based actions wrongly.

platform/platform-api/src/com/intellij/ui/DoubleClickListener.java

@@ -19,13 +19,40 @@
  */
 package com.intellij.ui;
 
+import javax.swing.*;
+import javax.swing.plaf.basic.BasicTreeUI;
+import javax.swing.tree.TreePath;
 import java.awt.event.MouseEvent;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
 
 public abstract class DoubleClickListener extends ClickListener {
   @Override
   public final boolean onClick(MouseEvent event, int clickCount) {
     if (clickCount == 2 && event.getButton() == MouseEvent.BUTTON1) {
-      return onDoubleClick(event);
+      return isExpandIconClick(event) ? false : onDoubleClick(event);
+    }
+    return false;
+  }
+
+  private static boolean isExpandIconClick(MouseEvent event) {
+    if (event.getComponent() instanceof JTree) {
+      JTree tree = (JTree)event.getComponent();
+      TreePath treePath = tree.getClosestPathForLocation(event.getX(), event.getY());
+      if (treePath == null || !(tree.getUI() instanceof BasicTreeUI)) return false;
+      BasicTreeUI ui = (BasicTreeUI)tree.getUI();
+      try {
+        Method method = BasicTreeUI.class.getDeclaredMethod("isLocationInExpandControl", TreePath.class, Integer.TYPE, Integer.TYPE);
+        method.setAccessible(true);
+        Object result = method.invoke(ui, treePath, event.getX(), event.getY());
+        if (result instanceof Boolean && result.equals(Boolean.TRUE)) return true;
+      }
+      catch (NoSuchMethodException e) {
+      }
+      catch (InvocationTargetException e) {
+      }
+      catch (IllegalAccessException e) {
+      }
     }
     return false;
   }