I executed uDig using a right-to-left language (I used the option -nl fa - fa for the Farsi language) and there is a big problem. I loaded a shapefile (usa_counties.shp) and tried to use "select feature" tool but it seems that coordinates are right-to-lefted too! The position box below the Map Editor shows the wrong position (mirrored position). When you click at the right side of the map editor, a feature in the left side get highlighted and selected!
To remake the situation just run the uDig using the option -nl fa, open a shapefile, and try to use the "select feature" tool on the toolbar.
Here is Jody's suggestion to resolve the problem:
a method for MapDisplay that returns the screen "orientation"
* an additional "flip" flag for the ScaleUtils.pixelToWorld method
* add a method ScaleUtils.pixelToWorld( x, y, bounds, size, orientation )