Steps to reproduce(http://youtu.be/9eT4vb9W6f0 ):
1. Open html file in our HTML editor(I use index.html from kitchensink html5 project), open jQuery mobile palette(version 1.3)
2. Collapse some element
3. DnD button into source. Wizard appears, button successfully added. BUT it droppen into incorrect place.
3a. Or press cancel in the wizard.
4. Try to repeat Step2. Cursor does not change, dropping is not available. Reopening file does not help.
Stacktrace from error log:

java.lang.IllegalArgumentException: Index out of bounds
at org.eclipse.swt.SWT.error(SWT.java:4422)
at org.eclipse.swt.SWT.error(SWT.java:4356)
at org.eclipse.swt.SWT.error(SWT.java:4327)
at org.eclipse.swt.custom.StyledText.getLocationAtOffset(StyledText.java:4353)
at org.jboss.tools.jst.web.ui.internal.editor.jspeditor.xpl.StyledTextDropTargetEffect.refreshCaret(StyledTextDropTargetEffect.java:222)
at org.jboss.tools.jst.web.ui.internal.editor.jspeditor.xpl.StyledTextDropTargetEffect.dragOver(StyledTextDropTargetEffect.java:208)
at org.eclipse.swt.dnd.DNDListener.handleEvent(DNDListener.java:84)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4353)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1061)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1085)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1070)
at org.eclipse.swt.widgets.Widget.notifyListeners(Widget.java:782)
at org.eclipse.swt.dnd.DropTarget.DragOver(DropTarget.java:366)
at org.eclipse.swt.dnd.DropTarget$3.method4(DropTarget.java:250)
at org.eclipse.swt.internal.ole.win32.COMObject.callback4(COMObject.java:101)
at org.eclipse.swt.internal.ole.win32.COM.DoDragDrop(Native Method)
at org.eclipse.swt.dnd.DragSource.drag(DragSource.java:363)
at org.eclipse.swt.dnd.DragSource.access$0(DragSource.java:289)
at org.eclipse.swt.dnd.DragSource$1.handleEvent(DragSource.java:172)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4353)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1061)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4172)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3761)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$9.run(PartRenderingEngine.java:1122)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1006)
at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:147)
at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:630)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:574)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:150)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:125)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:133)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:103)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:378)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:232)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:648)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:603)
at org.eclipse.equinox.launcher.Main.run(Main.java:1462)
at org.eclipse.equinox.launcher.Main.main(Main.java:1438)