Troubleshooting Citrix Xenapp Seamless Display Issues

References:

Seamless Configuration Settings for the Citrix Receiver for Windows

CTX127043 – Case Study: Troubleshooting Seamless Flag – Custom Application

Seamless Configuration Settings

Nested Seamless Sessions are not Supported

Certain Seamless Applications Experience a Fatal Error When Using Client Devices with Multiple Monitors

Seamless Focus Issues with Presentation Server Client 10.x

Application Not Refreshing Correctly Within an ICA Session

A Maximized Seamless Application Covers the Local Taskbar

How to Force a Published Application to Start in Maximized Mode with Seamless Mode Enabled

How to Allow More Memory for Session Graphics on Windows Server 2003

Citrix defines a seamless window as "setting you can specify for the window size of a published application. If a published application runs in a seamless window, the user can take advantage of all the client platform’s window management features, such as resizing and minimizing.", and seamless mode is enabled by default within Xenapp because it works well for most deployments.  Typical applications like Internet Explorer, or Notepad are not usually going to require any customization when it comes to seamless mode within Citrix.  It is your custom applications, or applications that were created many OS versions ago (and never updated) that are typically going to provide you with the most opportunity for headache.

A call that we see commonly in the Citrix support or consulting world can revolve around an application not displaying properly when launched.  This could appear as a blurryness issue, or the window is not sized correctly, or perhaps half of the application is missing from the window.  Ultimately the resolution for many of these issues is to tweak the seamless settings on the Citrix Xenapp server side using the seamless troubleshooting methodology.  Here is how I typically approach these situations:

Before starting down the path of troubleshooting, it is important to make sure that your deployment of Xenapp is patched to the most recent levels.  I am continuously surprised at how so many companies neglect to install current public hotfixes released from Citrix, or ignore the patching process all together.  At the time of writing this document, Hotfix Rollup Pack 1 for Xenapp 6.5 includes two very important fixes for seamless issues.  In addition to the rollup pack, there are already 18 posthotfix rollup pack 1 hotfixes available for download on the Citrix website.  I suggest taking a look at each of them, and evaluating if they would be a good fit in your environment before moving forward.  Also rule out the ICA Client you are using by installing the latest version of receiver and testing with that first.  If the problem goes away with the latest version of the Citrix Receiver — then chances are you've run into a problem or a limitation of the ICA client you are using.

1). Refer to the following registry key on the Citrix Xenapp server:

Registry Key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Citrix\wfshell\TWI
Value Name: SeamlessFlags
Value Type: REG_DWORD

2). Verify if there are already seamless flags on that key.  If so, be sure to record which flags are in use before experimenting with removing them one-by-one, testing between changes in order to see if one of the flags has caused the issue.

3). If step 2 does not resolve the issue, or if there were no flags to begin with — Insert the value of "3EFFB6", which is the seamless flag for all values combined. This flag is the catch-all flag provided by Citrix support to help us determine if our problem is a seamless issue at all.  If this change resolves the issue, we can move on to step 4.  If this flag does nothing, we can virtually rule out Citrix seamless flags as an option — and may need to troubleshooting elsewhere.

4). Once we've proven if the problem can be fixed by using a Citrix seamless flag, it is not an option to leave the catch-all flag in place as a permanent solution.  While you might be eager to set it and forget it, be warned that this is not best practice and is too top heavy to deploy in production.

5). A guess-and-check methodology should be followed from her to determine which seamless flag fixes the problem for a long term solution.  It's going to be a manual process, but once you find the individual flag, or flags that resolve the issue — you can leave those in the registry for testing in DEV, and eventually roll them to production if they pass your internal testing process.

Seamless Flag

Value

ALL VALUES COMBINED

3EFFB6

Allow AA Hook to handle Hide Events

3EFFB6

DISABLE CLIENT INFO SYNC EXCEPT CODEPAGE

1EFFB6

DISABLE CLIENT INFO SYNC EXCEPT WORKAREA

EFFB6

DISABLE LANGUAGE BAR AGENT

6FFB6

DO NOT SEND OFF SCREEN WINDOWS

2FFB6

DON’T SEND DISABLE

FFB6

DISABLE CLIENT INFO SYNC

7FB6

DISABLE SHELL HOOK AGENT

3FB6

FORCE MENU WINDOW TO HAVE OWNER

1FB6

DISABLE FULL WINDOW DRAG

FB6

FORCE RAW MOUSE EVENTS TO SERVER

7B6

DISABLE WM_QUERYDRAGICON MESSAGES

3B6

DISABLE LOAD CHECK

1B6

DISABLE ICONIC WINDOWS

B6

DISABLE SYSTRAY AGENT

36

ENABLE COLOR SYNC

16

DISABLE ACTIVE ACCESSIBILITY HOOK

6

DISABLE MODALITY CHECK

2

Keep in mind that if the issue you are working can not be resolved with a seamless flag, you may need to look elsewhere for a resolution.  Other "usual suspects" can include video memory issues, or client side problems.  In addition, there are some issues that are specific to certain EMR software packages, or even particular hardware (i.e. particular brands of thin client devices) — so be aware that the ultimate resolution may not lay with Citrix, and other vendors should be consulted as well.

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