I currently find it frustrating when making EQ adjustments to the PCEQ but having to close the gui when I want to solo (or mute) the track I'm working on.
 
It would be great to have dedicated buttons on the EQ flyout.

1000 times yes.

3rd party solution is already available; keep Duckbar running while using SONAR.
Duckbar adds SOLO and RESET eq buttons to the QuadEQ flyout window.
 

I would love this as well, in fact I see no reason why they couldn't have both solo and mute buttons on the flyout. It seems like the decent thing to do given that the flyout doesn't always "fly out" to the same side each time. This inconsistency is what makes it hide the buttons - it's fine when it flies out to the right but hides them when it flies out to the left. 
 
I can imagine that it might not be a trivial implementation from a coding point of view, because it may be the case that the Quadcurve code doesn't have ready access to the track controls. 

+1
 

Great idea Jonesy -  couldn't count the number of times a day I curse this! 

I think that every plugin or PC should include buttons like mute, solo, bypass and should be movable too. And there should always be some presets.

Yeah, I really like the solo buttons on the other VSTs.

Or if this and other PC modules had VST versions, then bam. Move the windows wherever you like. :)