1. Go to Debug mode.
2. Select "Window" -> "Views" -> "Debugger Log" from the menu.
3. Click into the the Debugger Log view.
4. Press Ctrl+F.
   The search bar appears:
   
5. Make the Debugger Log view bigger by pulling down its lower border.
   The search bar grows:
   

I don't see any advantage in the bigger search bar, please let me know if there is one. If there is none, then it should not grow at all.