It's impossible for some people with disabilities to hold down spacebar.
(Windows allows "sticky" keys for modifiers like alt, ctrl, shift, but not for spacebar).
The Windows On-Screen Keyboard will also toggle the modifiers' states, but not other keys (like the spacebar).
An on-screen tool for panning would be one option.
Depending on your UX needs, perhaps the option where spacebar would toggle the pan-with-click state. Or both of these options.
(While you're at it, if you wouldn't mind, please inform your UX/UI people they might like to evaluate the usability of the interface by disabled people -- on-screen-keyboards are one primary tool used by many.) Thank you very much for your wonderful work.