I am unfamiliar with global mouse hooks, but despite it intending only to capture the mouse wheel, is it perhaps preventing mouse click events from being passed further on down the chain to other mouse hooks?

I ran Synergy in Debug2 mode (as suggested by a member of the Synergy development team) and found that mouse clicks weren't being detected on the server. This brings up a possibility that the clicks are being blocked by 7TT, even if it is unintentional. As I understand it, such blocking would cause any other mouse hook app not to detect mouse clicks, not just Synergy.

So with some experimentation I discovered a couple of things:

• Synergy starts well before 7+TT, with clicking only ceasing to work when 7+TT starts and enables the mouse wheel features (as would be expected).
• Enabling the mouse wheel features after the PC starts with those features disabled results in the issue returning.
• If Synergy is restarted, even if mouse wheel features remain enabled, the problem goes away.
• Disabling and re-enabling the mouse wheel features causes the issue to return, even after Synergy has been restarted.
• Any instance of "mouse wheel features" can be replaced with "global mouse hook demo" and the issue is the same.

Seems like Synergy can deal with existing mouse hooks, but if one is set up while Synergy's server is running, it doesn't notice and can't deal with it... Time to take this to Synergy. :)

Any of the options in the 'Other taskbar options > Mouse wheel' section display the issue, I use the basic paid version of Synergy, but I'll find out if the free one has the same issue. :)

• Any clicks on the second PC's screen do not register, even on the lock screen when there is no taskbar.
• The issue goes away when all the options are turned off, I'll try and find out which it is that's causing the issue.