I wanted to make some speed lines to show something was moving. I kept getting kinks in my lines when I clicked at one end, held down the Shift key and clicked to the other side or down. I kept playing with it and discovered while holding down the Shift key, if I pressed the Ctrl key after I had reached the point where I wanted the line to end but before clicking with the mouse, the Ctrl key straightened out the line with no kinks. This is for horizontal and vertical lines. I don't think you need it for diagonal or slanted lines.

This may be somewhere in the manual and I may be repeating information.

I'm going to number the steps because that's a lot of steps in one sentence.

1. Use the Pencil brush (you can also use the Paintbrush) and click where you want the line to start.
   
   
2. Press the Shift key and move the cursor to where you want the other end of the line.
   
   
3. Before you click the mouse button, while still holding down the Shift key, press the Ctrl key.
   
   
4. Click the mouse button.

Attached PDF

Probably because just holding down the ctrl key will constrain Gimp to draw straight lines in one perfect direction.
Good find O!

It doesn't work with just the Ctrl key. You must have the Shift key working first, move the cursor then press the Ctrl key.


My show and tell.

My experience has been that holding down Shift, then the Ctrl key constrains the line to 15 degree multiples.

Ah! Another good thing to know. Thanks!

Indeed.

Shift-click draws a straight line for the last position of the brush in most "paint tools": pen, brush, airbursh, ink, erase, clone...

Ctrl- in many Gimp tools is "constrained angles": in the shift-click lines in the paint tools above, but also with the Blend, Rotate, Free-hand selection, Scissors (funny effect, try it...)

Yep works the same in Inkscape too.

I think I read that tip here somewhere