ident and tab for selected shape

[Örjan Skoglösa]

I would like to be able to insert an indent (with first line staying
at the left) and a tab (at the same position as the indent) with one
keystroke. I would like this to happen in the shape/paragraph where
the cursor/selection currently is located.

First I tried to simply record it, but as indentation only is possible
with the mouse on the ruler (?), it could not be recorded.

Then I tried to write some code for it, but I do not succeed without
really understanding what is going wrong.

Any hint or help very appreciated.

BR,
Örjan