I added a way to transform layers with the mouse by pressing the 'G', 'R' or 'S' keys to grab, rotate and scale the selected layers in a similar fashion to blender. I made shift slow the transformation speed by a tenth and ctrl to snap the transformation to intervals. I also allowed users to type in the value for the transformation with the number keys if they wanted a specific value and constrain their transformation to one axis with the 'x' and 'y' keys. You can try the build at https://714e13e8.graphite-master.pages.dev. This was one of my bigger PRs (Collaborating with pull requests - GitHub) at about 550 lines of code available at github.com/GraphiteEditor/Graphite/pull/356/files.
I worked closely with @Keavon to refine the UX with things like reversing an operation if you switch directly to a new transform operation, removing the negative when all numbers are deleted and ignoring presses to decimal point when there is already a decimal point.
I am doing lots of projects every projects all the time and I can't put them all on the website so I've made a blog.