example: 
working on edits for 3 clips in two tracks
constantly using control- left and right arrows to zoom
wanted to have a quick way to fit just the selected tracks to the window
 
any body know how to do this?

Hit Z once to switch to Zoom Tool (or just hold down Z) and then drag those three clips. Hit Alt+Z to restore the original state. For many (?) years this Z-drag didn't work properly when there was a hidden track or collapsed folder in the project, but fortunately the bug was fixed in the latest patch (Dorchester).
If you have Auto Track Zoom enabled, you must make either of the two tracks a current track first in order for the tool to zoom properly.