hello, I'm working on a customizable ruler coordinate system (see bug #170049: https://bugs.launchpad.net/inkscape/+bug/170049 ) and struggle with how to correctly use the gui elements in the document properties. I use ScalarUnit as number inputs. Clicking on up and down buttons works, but when entering numbers via keyboard nothing happens. I have not directly used signals but maybe I need to? I also uploaded the code on launchpad: https://code.launchpad.net/~vaifrax/inkscape/bugfix170049 <https://code.launchpad.net/%7Evaifrax/inkscape/bugfix170049> I'd appreciate a hint on how to (best) make keyboard input trigger the value change. Thanks