Chromebook: When hovering the cursor over the top of the screen of the Clip Studio Paint app, a white bar will appear over it
In Chrome OS, if Clip Studio Paint is in full screen (immersive mode), a white bar appears when you hover the cursor over the top of the screen.
Workaround
Pressing the Fullscreen key on the keyboard to release the full screen view, allowing you to work without the white bar covering the application.
Fullscreen key