romin and John,
Maybe Im wrong, but I still think the problem is the tab design and font rendering. The tab "title" space is fixed relative to the preset tab width by the user and there is only 1 line for Icon and text.
The Icon takes 'x' amount of space. The remaining space is available for text. It appears to me that after the Icon there isnt enough space to allow the display of any characters (or text). Thats why I suggested for verification just bump it out to something like 36 or 48 - you can always put it back.
This is a condition to what forces vertical scroll bars in Notepad. You can demonstrate this to yourself using Notepad.
- Type in a line of text.
- Copy it vertically several times.
- Drag the bottom of the text box up to the last row of text.
- Note: if you pull it up just a bit too far, the last line drops off and the vertical scroll bar appears. This is because the viewport cannot display the complete char box, so it doesnt display any (no half char).
This is what I was trying to explain in this image. There isnt enough space for 1 "full" character, therefore it wont display anything other than the full Icon (which there is enough space).
The only other thing I can think of is if you have the Currently selected tab set for BOLD, which will take more space too. That may be causing the overlap. Setting any text to bold will force the space available to increase in all directions.

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