When assigning vertexes to bones in weight binding, there's "no bone" weight to use. All vertexes have to depends on some bone in the binding. (All bones in the binding must be able to move vertexes) I expected like a grey colored assignment to be available so that it belongs to nothing. Is such an option exist somewhere? At first I thought "remove" tool would do this.

For example I would like to move the skirt with blue and pink bone. Both would get each side of this skirt, but moving it would make the top half of the skirt deform which it should not be. I would like that part to stay still and want to "remove" weights from both bones to nothing but that can't be done, so what I have to do is to always have a "no use" bone so that I can assign it to vertexes I don't plan to move.

In this image it's the purple cross hair bone. But I thought it is strange to have a bone for this purpose and I might miss something obvious that is already there in the program.

(Also the upload attachment button says "Sorry, the board attachment quota has been reached.")