I have various Safari windows, TextEdit docs, and Stickies notes that relate to different things (e.g. work, home). I want to split these across two Mission Control desktops depending on what they are for. On Mission Control, I can't seem to drag these separate windows or even whole apps (collection of windows via the icon) into a desktop - the drag action works, the plus square appears, but the item then just springs back. Same for hovering it at edge of screen.
Update: these apps had "Assign to All" set - changing to "Assign to None" via Dock did the trick :-)