Project: Eclipse_Platform_UI
Bug 55099 [DND] Holding the mouse down on an editor tab for too long will split the editor area.
Reported: 2004-03-17 10:09:27 | Status: resolved fixed

This may not be a DnD bug...just guessing. Ensure that you're using multiple editor tabs. Open multiple editors. Click and hold the mouse button on one of the editor tabs for a few seconds. Don't move the mouse. Release the button. The screen will split as if you had dragged the editor to a new position.

Files changed in fix:
bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/presentations/PresentationUtil.java