Please describe the problem:
I haved added an object from the UML stencil (e.g. the actor object). I now want
to edit its text property. It is not really clear when the application is in
'text editing mode' (a clue is that I can move the cursor using the cursor
keys). Now when I want to delete a letter in the text property, I press DEL and
the entire object is deleted.

Steps to reproduce:
1. Add object to diagram
2. Click on text
3. Edit text
4. Press Del


Actual results:
The object is deleted instead of a letter in its text property.

Expected results:
A deleted letter

Does this happen every time?
Yes

Other information:
If you fix this, please also consider hiding the objects sizer controls. That
way it is clear that a property of the object is now being edited and not the
object itself.

This will also help in indicating that a text is being edited.