Playback and selection

This really is two closely related feature requests. Both of them relate to playback, and how it's affected by the current selection. They're both small changes, but they'd save me a lot of frustration.

First, if I want to play a section of the score, I click at the point I want it to start playing from and then press play. But I have to be very careful what I click on, because it only works if I select a note head or a whole measure. If I instead select anything else—an accidental, a stem, a slur, etc.—then it ignores the selection and just continues playing from wherever it last left off. I suggest that if any score element is selected, that should serve to set the starting point for playback. Then I could just click wherever I wanted it to start, without having to be careful about exactly what I was clicking on.

The second request is about what sound it uses when I play on a MIDI keyboard. This is when I'm just playing to experiment with ideas, not in note entry mode. If I select a measure of one staff, then it plays using that staff's sound. But it only works if the current selection is a whole measure. If I instead select anything else, it ignores the selection and uses the sound of the top staff. So here again I suggest that if any score element is selected, it should use the sound of the associated staff. If I want to experiment with ideas for the cello part, I should be able to just click on the cello staff and start playing. I shouldn't have to be careful about exactly what I'm clicking on. Right now I have to be very careful about it, because if the click selects anything other than a complete measure, I get the sound of whatever is the top staff instead.