Only drag files when there are any files. 
Only drag files when there are any files. 
WoLpH/skim,WoLpH/skim,ycaihua/skim-app,WoLpH/skim,ycaihua/skim-app,WoLpH/skim,WoLpH/skim,ycaihua/skim-app,ycaihua/skim-app,ycaihua/skim-app