Add border/outline for ui.menu and ui.popup

[ascarter]

An outline border should be used when displaying ui.menu and ui.popup instead of relying solely on color. This is how the space bar menu and file picker work for example. These work just fine without having a background color to differentiate because the border makes it clear. The theme should support ui.menu.border and ui.popup.border to set a color like the window border on ui.window. I think using border makes it clear but whatever term fits is fine. If you want no border, make the color match the background color of ui.menu/ui.popup and it would disappear.

I have difficulties differentiating color so using styling and things like borders are much easier to perceive than trying to find colors to work. I use a very simple terminal theme that use the least amount of color I can. While I can find something to contrast, it would look much nicer to just have some borders here instead of having to choose a background color.

Example with LSP popup for Rust code. It's pretty much unreadable without using a background color

Example of the popup menu. Note that this is easily distinguishable because of the border and does not require any color background to work.

Example of the file picker also using border. This works easily as well.

[woojiq]

popup-border
https://docs.helix-editor.com/master/configuration.html

[ascarter]

Oh wow - sorry - I either missed that or it is new. Thanks!