It could be enough to just change the "Save" text to "Saving..." and gray it out, but that would not be very consistent. Perhaps the dialog with some sort of moving bar, if progress meter is not possible, could be enough.
It could be enough to just change the "Save" text to "Saving..." and gray it out, but that would not be very consistent. Perhaps the dialog with some sort of moving bar, if progress meter is not possible, could be enough.