I'm running Win 8.1 32b at 1920x1200, but this is a multi-boot PC with multiple version of Windows. Booting to Win 10 64-bit has the same problem (launches same instance of uT).
If uTorrent window width is less than ~1220 pixels, the search control begins to creep into the toolbar as the window is re-sized. My uT window is ~1050 pixels wide.