Usability Review & Feedback

Foreword

First of all, thanks for providing this great web app!
Below you will find a compact review and some feedback, most of it pretty self-explanatory.
If you'd like to follow up on any of these concretely, feel free to make standalone issues from them.
And in those issues feel free to ping me via an at-mention for further input or review if desired.

Elements as vector objects which remain editable/move-able (as opposed to destructive editing)
Infinite canvas - On export it is as large as it needs to be to fit all content
Local Storage + Nice URLS to local storage - Wow! Nicely done!

Various Comment Types to conveniently paste it into the markup/environment of your choice

Panel in 3 sizes: Closed (as floating action button) > Normal Tool Panel > Tool Panel with Help
Dialogs remember the last choices (e.g. Comment Types in Export dialog)
Holding down alt showing shortcuts near tools
Letter input changes Freeform character. Does that only when Freeform tool is selected to not be in conflict with other tools/modes/shortcuts.

Side panel should have inner scroll: With many files or with help open on small screens it is cut off.
File renaming dialog: ESC bound to "Cancel", ENTER should be bound to primary action (Create / Rename).

Tool shortcuts
- ALT 1-6 as shortcuts for the tools is not a good mnemonic.
- Should better be letters corresponding to the tools, idealy compliant with conventions of design apps. I propose the following:
- alt-R Rectangle - Rectangle is the generic form, square the special form, achieve 1:1 aspect ratio with shift-key down
- alt-O Oval - Again the name of the generic form, a circle the special form, plus the letter "O" has the shape of an oval too as an additional mnemonic.
- alt-V is the standard in design apps for the selection tool, V has a pointer/arrow-like shape.
- alt-F Freefrom
- alt-A Arrow
- alt-L Line
- alt-T Text
Pan & Zoom
- Uses outdated interaction scheme from 1990ies design apps and desktop publishing apps: SPACE to pan, scrollwheel to zoom.
- On devices with multitouch-trackpads, standard since ca 2010, this would be the more contemporary UX: Two-finger scrolling (on X and Y axis) + pinch-gesture for zooming in/out (Z axis).