This post explains how to launch Desktops and Applications in Windowed Mode using specific resolutions or a percentage of the screen.
By default when we launch applications and desktops they launch seamlessly as if running on the local endpoint. If applications and/or desktops behave in a way were seamless does not suit, you may want to consider launching those problematic resources in Windowed Mode instead.
Launching in Windowed Mode is easy and can be set up per resource. You can either define a static resolution or define a percentage of the screen.
On your StoreFront server(s), navigate to C:\inetpub\wwwroot\Citrix\CitrixStore\App_Data.
Note: Your path will be different depending on your Store name.
Now launch default.ica in a text editor.
To set a specific resolution underneath Application= type in brackets [] the name of your application as displayed in Citrix Studio. Underneath type the [Application] name type:
TWIMode=Off
DesiredHRES=
DesiredVRES=
The resolution is up to you.
Save the default.ica file. The next time youu launch a resource it will display as below in Windowed Mode: 
To set the Windowed Mode as a percent of the screen, replace DesiredHRES= and DesiredVRES=with ScreenPercent=. This works well especially for published desktops. 