In the latest Inkscape version 0.92, when I draw a straight line and want for instance to
make it longer/shorter, I use of course first F1, select that line and on both ends "handles" appear.
Then selecting one of the handles with my cursor to modify the line those "handles" disappear
and I find this very annoying. Is there a way to "restore" this?

What about selecting your line with the mouse and press F2 and then dragging the handles...?

theozh wrote:What about selecting your line with the mouse and press F2 and then dragging the handles...?

Thanks theozh, that is the solution solving my problem .

You're welcome!
Just as a general suggestion... You might want to prepend [solved] to the title of your first post. So, people quickly see in the overview: problem satisfactory solved, no more help needed... and people having the same problem can expect a solution in this thread...
If I browse the forum from time to time for interesting titles I prefer to know beforehand whether it's worth opening the thread because I can expect a satisfying answer

theozh wrote:You're welcome!
Just as a general suggestion... You might want to prepend [solved] to the title of your first post. So, people quickly see in the overview: problem satisfactory solved, no more help needed... and people having the same problem can expect a solution in this thread...
If I browse the forum from time to time for interesting titles I prefer to know beforehand whether it's worth opening the thread because I can expect a satisfying answer

Done!