Update the z-index value of the settings menu

[hilaryhacksel]

Resolves #661

[mention-bot]

@hilaryhacksel, thanks for your PR! By analyzing the annotation information on this pull request, we identified @vanessayuenn, @xorgy and @clbond to be potential reviewers

[sumitarora]

[xorgy]

In the future we should perhaps reorganize and document the various Z indices of things, but this should be good enough for now.

Though this change is probably enough, I think that there should only be one dropdown/context menu on the screen at once, so you can afford to put it much higher (say, 1000) which gives us much more room to stack other things.

[igor-ka]

@xorgy do you want changes made to this PR? If not, @hilaryhacksel let's merge it and move on for now.

[xorgy]

I would prefer the z-index be set more than 1 greater than the thing it was conflicting with, so that we can put something in between them in the future.