mixxxdj/mixxx — pull request #222 by rryan (2014-04-05 19:37:03+00:00)
Title: Eliminate unnecessary widget renders from control changes.

Instead of re-rendering on every control change (via
WWidget::onConnectedControlChanged), check for changes in what we would render
first.

Updated: WDisplay, WKnob, WKnobComposed, WSliderComposed, WStatusLight
Left unchanged: WWaveformViewer, WPushButton, WOverview, WVuMeter