Operating system: Windows 10 1803
Graphics card: nVidia RTX 2070
Broken: v 2.80 as found on the splash screen
The Object Mode drop down menu in the 3D viewports does not properly resize itself if the user picks a larger font point size in the Themes section of the preferences. Instead of resizing the control truncates the overrunning text with a square character.
Exact steps for others to reproduce the error
In Preferences \Themes \ Text Style change the Widget Points setting from the default of 11 to a larger value. I used 15.