Use icons for vertical tabs ? Like Files/Git/Extensions

[hexa00]

Should we use icons for these ?

It would look nicer and take less space.

[spoenemann]

I already prepared the CSS and TS code to enable this. Using icons in the side bars can be enabled by changing the display property of .p-TabBar.theia-app-sides .p-TabBar-tabIcon in sidepanel.css.

Of course that makes sense only if the widgets have icons. Currently Files, Git and Extensions have no icon.

[svenefftinge]

The recently introduced toolbar contributions are very useful and it is somehow odd, that we don't show them for widgets attached to the side panels (because we don't know where to render them).
If we go with the VS Code way, of having Icons in the vertical tabs, a hover showing the full label and a first row with the label followed by the tool bar icons this would be solved. Given that people have asked for the icon option over time, we might just go down that path and make it the default.

TLDR: Let's make vertical tabs showing the icons and add a first header row to all widgets, where the toolbar is shown on the right.