DnDTabbedPane. Idx for insertion selection fix.

[AndreiKud]

Hello. Thanks for maintaining this repo! I brought two minor improvements for DnDTabbedPane component.

1. Stopping traversing components after forward/backward buttons are already found.
2. Fixed incorrect tab insertion idx selection, when a small tab comes before a big tab (more than twice higher/wider)
   Bug:
   
   Fix:
   

Previously we checked tab rect by translating it backward by its half. I suggest checking halfs of the rect within original bounds. Explicit check for last tab remains the same, but extended to full width instead of half.

[AndreiKud]

@aterai you will check it when you have time, right?

[aterai]

you will check it when you have time, right?

Yes, I will check it from now on as I may have time this weekend.

[aterai]

I was able to reproduce the bug in my environment and confirm that the fix works fine.