I have a dual screen computer and recently noticed that when using seamless applications with the Citrix Online Plugin I could not move the application to my second screen.
After a bit of digging I found this issue was related to a “graphics memory” setting for the Farm
By default Citrix limits the maximum memory for a sessions graphics to 4Mb however this is not large enough for a high resolution application on a dual screen setup.
There are two possible solutions with Access Management Console
1) For the effected application(s) reduce there colour depth
Right-click on the application => Properties => Appearance => Set lower than 24-bit
2) Raise the session graphic memory limit from 4Mb to 8Mb
This can either be done at farm level or server level
Right-click either the farm or server => Properties => Display (under Server Default) => set the max memory to use to 8192