Patch Set 5: I would prefer that you didn't submit this; Unclean IP, do not check in

- we need a CQ for this change

we are getting closer :-) 

but there are still some issues to sort out:
- I feel the feature that editing the tag name edit field
  filters the list of existing tags is not obvious. 
  I first had the impression that something is weird here, 
  after playing around I discovered that this is filtering 
  and not a bug. IMHO it's a good idea but somehow this 
  needs to be made more obvious.
- I think the dialog title should be just 
      Create tag on branch "xyz"
- when trying to replace an existing tag I would expect that
  the fields switch to read-only automatically when the tag
  name field is equal to an existing tag name, having to
  select the existing tag for that requires too many clicks
  and doesn't feel intuitive
- I was not able to actually replace an existing tag since
  there seems to be no way to enable the OK button when the
  force checkbox is checked
- the following sequence leads to a stack overflow :
  - Team > Create Tag ...
  - enter a tag name
  - press tab to jump to the next input field
  -> this throws
java.lang.StackOverflowError
at org.eclipse.swt.widgets.Control.isEnabled(Control.java:1660)
at org.eclipse.egit.ui.internal.dialogs.CommitCombo.isEnabled(CommitCombo.java:207)
at org.eclipse.swt.widgets.Control.isEnabled(Control.java:1661)
at org.eclipse.egit.ui.internal.dialogs.CommitCombo.isEnabled(CommitCombo.java:207)
...