Sorry it took me 4 months to notice your problem Previous.
v1.4:
Locked the locale to US (solves a few minor UI bugs, I don't have alternate translations anyway).
Fixed a bug in the secondary mask option where it would not always enable correctly.
Fixed a bug where the sprite on the edge of a sheet caused the program to seize up (it was a simple fix).
Added a file chooser to import a sprite.
Added an option to sample the (center of the) edges and corners to determine background color (uses the one that occurs most often).
Added an generic error message system so that bugs are easier to report.
Uses Java 6
Watched a movie, then I got to fixing this, then I got done fixing it. Here you go, all fixed (in theory).
Download
v1.4:
Locked the locale to US (solves a few minor UI bugs, I don't have alternate translations anyway).
Fixed a bug in the secondary mask option where it would not always enable correctly.
Fixed a bug where the sprite on the edge of a sheet caused the program to seize up (it was a simple fix).
Added a file chooser to import a sprite.
Added an option to sample the (center of the) edges and corners to determine background color (uses the one that occurs most often).
Added an generic error message system so that bugs are easier to report.
Uses Java 6
Watched a movie, then I got to fixing this, then I got done fixing it. Here you go, all fixed (in theory).
Download