Currently, backgrounds are listed by their name only. I do notice backgrounds associated with either the level's theme, or the currently-selected style for the piece selector (I'm not sure which, as whenever I've been paying attention to backgrounds, both of these have been the same anyway), get brought to the top of the list.
Very understandable that, for an optional "pick one of these per level" feature, there's no full-blown menu or seperate dropdown or anything to select a style, then select a background from it. However, in order to save the background info into the level file correctly, the editor must internally know which style each background is associated with. So - could that not be added to the info displayed in the dropdown? Eg: Instead of the Abstract tileset's background just being listed as "colors", it could be listed as "namida_abstract:colors" or "colors (namida_abstract)" or something like that - personally I'd be in favor of the tileset name coming first, but let's see what others think re: that.
Severity: For me, minor. I'm generally working with 3-4 tilesets at a time, and rarely use tileset mixing. For creators who like to make things more complex and/or use a wider variety of styles at a time, I could see this getting frustrating.
