Keep keyboard focus on Add button

[mjulius]

Until around two weeks ago, when adding tags to an object the Add button in the Properties/Memberships side panel was keeping the keyboard input focus when the tag dialog was closed. This allowed to quickly enter a bunch of tags by just hitting Enter to get a new tag dialog without needing to bother the mouse.

Just in case the above is unclear this is the work flow that could be used:

• click Add
  
• enter key
  
• hit Tab
  
• enter value
  
• hit Enter to close the dialog
  
• hit Enter again and a new dialog pops up <-- this is the step that does not work anymore
  
• enter key
  
• ...

It is not a huge deal but it would be great if the previous behavior could be restored.

[Gubaer]

(In [2473]) fixed #3943: Keep keyboard focus on Add button