[General] Fix PTSDK-119 - Prevent changes when in code or preview
[General] Fix PTSDK-119 - Prevent changes when in code or preview

To prevent drag-n-drop of palette items when in code view or
preview, the palette items are all disabled when the design view
is not visible, and enabled when it is.

Signed-off-by: Shane Bryan <bb9fedbb0bee6c6c53f32da7fce5f936ef59aaaa@intel.com>

byjg/rib,b-cuts/rib,2braincells2go/rib,b-cuts/rib,Galen-Titanium/rib,crazyart/rib,taubmann/rib,xuqingkuang/rib,01org/rib,suoko/rib,cubemoon/rib,taubmann/rib,wuyongfeng/rib,crazyart/rib,jmptrader/rib,modulexcite/rib,eaglebk/rib,Galen-Titanium/rib,KevinChanH/rib,amithnair/rib,maxyu/rib,xuqingkuang/rib,2braincells2go/rib,Safiya85/rib,pplaquette/rib,amithnair/rib,suoko/rib,pplaquette/rib,01org/rib,zhizhangchen/rib,modulexcite/rib,modulexcite/rib,suoko/rib,2braincells2go/rib,amithnair/rib,vevedh/rib,cubemoon/rib,b-cuts/rib,carlst/rib,eaglebk/rib,smallertomato/rib,DonnaWuDongxia/rib,jsphkhan/rib,xuzhang/rib,smallertomato/rib,VIP000/rib,jmptrader/rib,vevedh/rib,KevinChanH/rib,byjg/rib,Safiya85/rib,xuzhang/rib,ndkeren/rib,jsphkhan/rib,jmptrader/rib,DonnaWuDongxia/rib,maxyu/rib,ndkeren/rib,01org/rib,KevinChanH/rib,crazyart/rib,wuyongfeng/rib,VIP000/rib,carlst/rib,Galen-Titanium/rib