OpenRCT2, v0.2.5-34-g56e6ec2c2 (56e6ec2 on develop) provided by GitHub
Windows 7 (x86-64)

Fullscreen (borderless), software (hardware rendering).

Place an object above ground to trigger the height indicator field. Move mouse extremely quickly over to the scenery window. The above shown glitch will appear.

Not easy to reproduce!