Is it possible to add extensions to svgcanvas?

[JonasGruenwald]

I'm using the svgcanvas on its own, and I would like to add functionality to place a triangle shape, similar to the built in rect and circle shapes.

I noticed that the default extension 'ext-polystar' already has functionality for this, however as it seems, default extensions are not loaded when just using svgcanvas without svgedit - and I can't seem to find a way to load it, I tried using the extensions array in the config and placing the extension in my project at the appropriate place.

Is it at all possible to add extensions to just svgcanvas?
It seems like the ext-mouseDown and ext-mouseMove functions are not exposed on the canvas itself, just for extensions somehow, how can I add my custom shape tool to the canvas?