Monocolor freezes with apply_amount error if you move Amount slider with the Display Preview or Display Input and Preview buttons pushed down.
With the Synchronized Scrolling button pushed up the tranformation generates an error thumbnail after a while and the dialog is accessible again
With the Synchronized Scrolling button pushed down the application might also recover after the apply_amount error message with Apply amount mask bar behind it appear and is clicked on several times.
I have not encountered this problem with 24 bit images.
Monocolor freezes with 48 bit images
Moderator: jsachs