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  1. JDK
  2. JDK-8275039

WInputMethod hangs if an AWT Frame appears under a drag

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    • Subcomponent:
    • CPU:
      generic
    • OS:
      generic

      Description

      ADDITIONAL SYSTEM INFORMATION :
      Windows 10, Java OpenJDK 64-Bit build 16+36-2231

      A DESCRIPTION OF THE PROBLEM :
      If a file drag is happening and an AWT Frame is shown under it, the EDT hangs forever.

      This happens quite often in real world applications. For example, a user starts an app, then starts dragging a file with the intent to drop it on the app after the window appears.

      STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
      Run the attached code. During the sleep, drag a Windows desktop icon to the screen center, so the JFrame appears beneath it.


      EXPECTED VERSUS ACTUAL BEHAVIOR :
      EXPECTED -
      The window to appear and the EDT to continue as normal.
      ACTUAL -
      The window appears, but the EDT hangs in WInputMethod#createNativeContext(). This happens every time.

      ---------- BEGIN SOURCE ----------
      import javax.awt.Frame;
      import java.awt.EventQueue;
      import java.awt.dnd.DnDConstants;
      import java.awt.dnd.DropTarget;
      import java.awt.dnd.DropTargetAdapter;
      import java.awt.dnd.DropTargetDropEvent;
      public class Test {
      static public void main (String[] args) throws Exception {
      Thread.sleep(1000);
      EventQueue.invokeLater( () -> {
      var frame = new JFrame();
      new DropTarget(frame, DnDConstants.ACTION_COPY_OR_MOVE | DnDConstants.ACTION_LINK, new DropTargetAdapter() {
      public void drop (DropTargetDropEvent event) {
      }
      }, true);
      frame.setSize(1024, 768);
      frame.setLocationRelativeTo(null);
      frame.setVisible(true);
      });
      }
      }
      ---------- END SOURCE ----------

      CUSTOMER SUBMITTED WORKAROUND :
      There is no workaround, the app is broken and Java must be forcibly terminated.

      FREQUENCY : always


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              Assignee:
              pnarayanaswa Praveen Narayanaswamy
              Reporter:
              webbuggrp Webbug Group
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                Created:
                Updated:
                Resolved: