Global Zoom/Expand level slider

[hojberg]

In the top toolbar of the workspace, a slider should be visible with 3 levels for: fully collapsed, definition expanded, definition and source expanded.

Using the slider should overwrite any local expansion levels (verify if this is a good ux).

This global level can also be changed from anywhere by holding a modifier (Z? Ctrl?) and scrolling with the mouse. Z then 1, for zoom level 1 could perhaps also be worth while?

This needs to interplay with keyboard shortcuts for the local definition zoom level in some way.