webgui: provide longer comments for TCanvas data members
webgui: provide longer comments for TCanvas data members

Use extra ///<! comment if member should be removed from I/O
root-mirror/root,olifre/root,zzxuanyuan/root,zzxuanyuan/root,olifre/root,zzxuanyuan/root,karies/root,karies/root,root-mirror/root,karies/root,zzxuanyuan/root,olifre/root,root-mirror/root,karies/root,root-mirror/root,zzxuanyuan/root,root-mirror/root,zzxuanyuan/root,olifre/root,olifre/root,karies/root,olifre/root,karies/root,zzxuanyuan/root,karies/root,root-mirror/root,karies/root,olifre/root,zzxuanyuan/root,root-mirror/root,olifre/root,olifre/root,karies/root,zzxuanyuan/root,zzxuanyuan/root,root-mirror/root,olifre/root,root-mirror/root,karies/root,olifre/root,root-mirror/root,root-mirror/root,zzxuanyuan/root,karies/root,zzxuanyuan/root