Controls in Staff Text Properties non-intuitive

Ubuntu Studio 14.04, GIT commit: 9195a9f

Not a big deal, but I find the need to explicitly click a voice button to be non-intuitive. I see lots of users selecting "Pizzicato" (or whatever) in the drop down, hitting OK, then wondering why it doesn't work. I understand we need "no-op" to be the default. We have to solve similar problems for the other tabs - and will have to do so again when we add a "Swing" tab. Right now it's a hodgepodge of different approaches, Maybe we need one well-designed approach?

For Change Channel, I'd propose voices 1-4 on the first dropdown all be enabled by default, but there be a global "Enabled" checkbox for the tab (like the "Change Stops" for Aeolus) to control whether the tab takes effect all all. And making any change within the tab automaitcally checks the "Enabled" box. Other tabs would use a similar model.