Allow selection in selection tool mode to go "negative". 
Allow selection in selection tool mode to go "negative". 
WoLpH/skim,WoLpH/skim,WoLpH/skim,ycaihua/skim-app,ycaihua/skim-app,WoLpH/skim,ycaihua/skim-app,ycaihua/skim-app,WoLpH/skim,ycaihua/skim-app