After another week, I successfully added a basic language to write
own scripts and macros in Javascript running in a sandbox which has an API to the spreadsheet and access to all basic window methods.
How a macro looks like:
The above macro takes the current view of the user and flashes the whole background with random colors and numbers.
You can run and edit scripts in the script manager. Click on the tab called "Script". On the right bottom you can see a whole module - to execute it click on "MainScript" and on the run button (the button with a play symbol).
I also added a modularity, so clients can create modular marcos like include functions defined in another macro.
Copy, Paste and Cut Out Cell fields run stable now.
Modals are responsive now and looks more fresh, also the UI font got changed to Robodraft.
The Undo and Redo stack got extended to support column & row resizing, insertion and deletion.
I added natural order recalculation, so deep formula cell references get properly calculated.
As always a billion bugs got fixed.