Mask Editor Plugin
This plugin is designed to manipulate binary masks over images. It contains all the basic tools to manage such objects.
Notes for developers
Otherwise, the source code is always provided inside the jar file of the plugin. If you are interested in developing plugins using the MasckStack structure, you should have a look at the plugins.nherve.toolbox.image.mask package in my toolbox. You may also check KMeans Color Quantization and Color Picker Threshold plugins that are both based on it.