R=rsc CC=plan9port.codebot http://codereview.appspot.com/5505091

The Finder can be reactivated after Devdraw's activation if both windows are on the same space. We prevent this by preventing Plumb.app's activation in the first place. R=rsc CC=plan9port.codebot http://codereview.appspot.com/5498096

(The new variable "willactivate" is in the input structure "in", which is illogical. But this structure will soon be renamed "app". I postpone the renaming to avoid conflicts with simultaneous Codereview issues.) R=rsc CC=plan9port.codebot http://codereview.appspot.com/5504102

R=rsc CC=plan9port.codebot http://codereview.appspot.com/5503086

R=rsc CC=plan9port.codebot http://codereview.appspot.com/5507045

R=rsc CC=plan9port.codebot http://codereview.appspot.com/5500090

R=rsc CC=plan9port.codebot http://codereview.appspot.com/5491051

Typographers say its wrong. R=rsc http://codereview.appspot.com/5517046

This problem happens especially in fossil/view when vtread can be called even if not connected to venti. The old libventi handle this case properly in the function vtRPC, which is called by vtReadPacket (client.c). R=rsc CC=plan9port.codebot http://codereview.appspot.com/5484044

R=rsc CC=plan9port.codebot http://codereview.appspot.com/5356050

R=rsc http://codereview.appspot.com/5480055

R=rsc CC=plan9port.codebot http://codereview.appspot.com/5451114

R=rsc CC=plan9port.codebot http://codereview.appspot.com/5440107

R=rsc CC=plan9port.codebot http://codereview.appspot.com/5451052

R=rsc CC=plan9port.codebot http://codereview.appspot.com/5434052