NOTE: This is the newer AutoCAD-like trim command next to the old one, not the traditional TC trim command.
Attempting to click on a spline after doing <select all> to select all as cutting edges induces an Unhandled Exception error. Attempting to do this with a bezier does not crash the program, but no trimming happens.
The tool works fine when selecting a cutting edge first, then trimming either type of curve. And regular lines trim fine, even using curves as cutting edges or doing <select all>.
Not a huge deal, but just wanted to pass on the info.