copy buttons do not always set the source correctly

[ssube]

The copy to img2img and copy to inpaint buttons do not always set the source property correctly, so clicking that button and then clicking Generate without adjusting any parameters will not send a request, no loading card appears, and nothing actually happens. The console errors indicate that the source property is usually empty at that point.

[ssube]

This seems to be a problem with the inpainting mask, in particular. I have not been able to reproduce it recently with img2img mode, but copying an inpaint source and then sending the request without editing the mask at all will break things.

[ssube]

Copying a new source image to the inpaint tab now clears the mask and marks the canvas as dirty, so the newly-clear mask is saved to state, and the button works immediately without any painting or adjusting of the settings.