This library came about as I found selecting and manipulating existing MapTool drawings/templates difficult.
With this lib you can get drawings at a mouse clicked point on the map or within a mouse click+drag defined area and then manipulate them (using some of MapTool's existing drawing functions behind the scenes).
You can also define you own color or asset palettes (the latter via a MT table), and have different palettes for the pen and the fill.
Run the "Read Me!" macro for more info.
Also note that it links overlay co-ordinates to map co-ordinates, which isn't really supported by MapTool, but it works as of 1.16.2.