-Finds the union of this region and the the non-transparent pixels of a
-bitmap. If the bitmap has a mask then it will be used, otherwise the
-colour to be treated as transparent may be specified, along with an
+Finds the union of this region and the non-transparent pixels of a
+bitmap. Bitmap's mask is used to determine transparency. If the bitmap doesn't
+have a mask, solid rectangle of bitmap's dimensions is used.
+
+\func{bool}{Union}{\param{const wxBitmap\&}{ bmp},
+ \param{const wxColour\&}{ transColour},
+ \param{int}{ tolerance = 0}}
+
+Finds the union of this region and the non-transparent pixels of a
+bitmap. Colour to be treated as transparent is specified in the
+\arg{transColour} argument, along with an