Made several changes with the introduction of STTime class, which belongs to STPlotWidget, can be edited by STPlotEditor, and controls the time window for every pv added. STColorButton appears in STVariableEditor and is supposed to allow the user to select a series color from a color dialog and provide feedback, but isn't finished yet. STListView appears in STVariableCollectionEditor and mainly provides an alternate way to add pvs through a context menu (a little buggy, commented out for now).