1 - Pick off tracks to be affected. Either Ctrl Left Click and Select each track header OR Shift Click and PICK off Events. Anything that the T/L Cursor is "over" will be selected.
2 - Right click on one of the items in 1 above.
3 - Make Group: Either drop down menu select Group OR "G"
4 - Go to the Right end of any of the now "Grouped" events OR Tracks and display the double headed arrow; hold down Ctrl + Left Mouse button and drrraaag to the right!
Play around with this a few times.
WHat you'll recognise happening is rather interesting. EVEN Event length events will be stretched evenly - BUT, and this is a good thing, UNEVEN event length will be, of course, stretch in their ratio length to each other!!! Gaps will also increase relative to the gaps elsewhere - as part of the Group. NOW . . try "squashing the same group - WOAH! - Good eh?