dragging a room from one section to another can result in flickering

[uhoreg]

as reported by temsmeding in https://matrix.to/#/!DgvjtOljKujDBrxyHk:matrix.org/$14950470741847448GElGx:matrix.org, and as seen in https://matrix.org/_matrix/media/v1/download/matrix.org/EExFlTxOsvaCBbXjmTCoqQLD

[tomsmeding]

I have this issue in Firefox 53.0.2 and Safari 10.1.1 on OS X, if relevant.

[tomsmeding]

More info: this only happens if, apart from the room being dragged, both the source and the target section are empty. Otherwise, no flickering occurs.

[t3chguy]

I reproduced this on Chrome on Windows

[turt2live]

Duplicate of #3370, related to #3280

Edit: Although the flickering is odd - I wonder if that's still related to #3370?

[uhoreg]

I don't think it's a dup of #3370. I think it's just caused by the fact that when you drag rooms between empty sections, the size changes due to the drag hint, so if the mouse is in the right spot, then the section that the mouse is over will constantly change.

[lampholder]

P2 rather than P1 just because (presumably) people don't see it that often?

[turt2live]

Closing in favour of #8614