How to run the whole currently open script?

I know I can run the current marked lines etc.

But how can I run the whole currently open script no matter where the cursor is or what is marked/highlited?

You can click the Source button if working in the RStudio IDE.
image

It is Ctrl+Shift+S
The button is in the Editors Window toolbar on its right end.

btw: Do I see it right that the RStudio "GUI" is build from HTML not from a full GUI library like Gtk, Qt , ...?

That may explain why I can't find an option to modify the size of the toolbar buttons?