Scroll Horizontally on Timeline of Final Cut Pro WITHOUT Holding Shift

Final Cut will work with Sticky Keys.

If you do not have Sticky Keys enabled:

Go to  > System Settings (or Preferences depending on OS version)

Click on Accessibility.

Make sure Sticky Keys is selected in General, then scroll down the list on the left and select Keyboard.

To the right of Enable Sticky Keys checkbox, select the Options.

Select the Press the Shift key five times to toggle... then OK. I recommend that Display pressed keys on screen is also enabled. Click OK.

[By the way, Sticky Keys seems to activate at 3 Shift key taps. You'll get a Sticky Keys On sign mid-screen when it activates.]

Now, in FCP, you can type the shift key 5 (or 3) times to activate sticky keys, press the shift key again, then scroll. When you're done, tap the shift key again (I think it's about 3 times) until the you get the Sticky Keys off sign mid-screen.

Sticky keys may take some getting used to... For example, if you see the shift key sign at the top right of the screen, you'll want to dismiss it (by typing the shift key again, once) before you use Command key combinations (unless you need the shift key in the combination.) And, Sticky Keys can be annoying if it's left on while typing if you need to use the "regular" shift key... stuff like that. It is, however, there if you need it.

Hope this helps...