Suppress warning message about turning tk-related devices OFF for the case when they are all OFF already.
Suppress warning message about turning tk-related devices OFF for the case
when they are all OFF already.

svn path=/trunk/; revision=7975

FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot,FreeScienceCommunity/PLPlot