System Information
Operating system: Windows-10-10.0.19041-SP0 64 Bits
Graphics card: GeForce GTX 1060 6GB/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.38
Blender Version
Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-10-03 22:33, hash: rB6f3a9031f7b9
Caused by rBbbb2e0614fc3: Performance: Draw play head as an overlay
Short description of error
In Timeline, Dope sheet and NLA Editor you have a slider at the right that just shows when you come close.
Butr this slider then covers the little button to reveal the sidebar. The button remains clickable. But requires a bit aiming now, since you can't see the button anymore under the slider.
Exact steps for others to reproduce the error
[Please describe the exact steps needed to reproduce the issue]
[Based on the default startup or an attached .blend file (as simple as possible)]
Open Blender, switch to one of the editors, move the mouse to the right to reveal the slider. Watch the button disappear.
