Resizing the Editor window causes flicker effect

Resizing the Editor from 3 out of the 4 corners causes a flicker effect on the Editor window. The bottom right corner works normally but the other corners causes flickering.

Link to video example: [Link Removed]

1. Grab any of the 4 corners of the Editor window
2. Move it around to resize the window

Results: 3 out of the 4 corners have a flickering effect when resizing. Only the bottom right corner seems to work as normal.

Expected: That all 4 corners of the resizing tool would work like the bottom right corner does.