Lewis' Blog Tales from the trenches of information technology


Mozilla Hardware Acceleration and VNC sessions

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I've been a Mozilla user since before Mozilla. I was a Netscape user back in the early days of Netscape for OS/2, when WebExplorer was kind of neat, but Netscape was much better.

Well, as an avid user and supporter of SeaMonkey, both personally and professionally, I was pleased to see us (the SeaMonkey community) stay on the same Gecko with 2.1+ as Firefox 4+. One of the nice things introduced in Gecko 2 is hardware acceleration. Unfortunately, I have suffered with some nasty screen corruption on my ThinkPad T43 (SXGA+ 1400x1050, ATI Mobility Radeon X300) with hardware acceleration enabled (as it is by default). Mainly, this corruption manifests itself as mouse artifacts (droppings?) in the browser window and particularly in expanded menus. However, as this seems to only be happening on my T43 under eComStation 1.2R (one of these days, I'm going to upgrade eCS on this notebook to 2.1), I don't give it much thought when upgrading Mozilla apps on other systems, and leave acceleration set to the default.

BTW, to disable (hardware) layer acceleration, simply toggle the user pref layers.acceleration.disabled to true. See more on this, below.

I recently re-worked a ThinkPad X61s for a colleague, whose "other" IT guy seemed to have made a mess of things (Microsoft Philosophy: If something isn't working right, and a reinstall of an application doesn't fix it, blow away the operating system and start over, without regard for the preservation of user data and preferences; Novell & IBM Philosophy: If something isn't working right, fix what's broken). In the course of my rollback and recovery, I naturally updated all of the standard apps on the machine (this was originally a Vista Business preload, which I "downgraded" - truly an oxymoron - to XP Professional when I originally set up the notebook), including SeaMonkey and Firefox.

After handing off the box last night, my colleague emailed me to remind me that he never got the new server certificate installed for our mail server. I had forgotten to check that, myself (I had him disable TLS several months ago, until I could walk him through it over the phone, and had since let the issue drop entirely). I advised him that I would connect to his machine remotely to see to installing the new certificate.

Upon connecting to his system using VNC, I saw that he had SeaMonkey 2.3.3 open (one of the apps I updated while I had the ThinkPad), however, it appeared to be unresponsive. Nothing I clicked seemed to do anything, however, I could control the task from Task Manager. The screen simply would not update for SeaMonkey once launched. Moments later, it dawned on me that hardware acceleration might entirely bypass VNC.

I closed SeaMonkey from the task manager, and opened Notepad. From there, I drilled down to the seaMonkey profile directory, and opened prefs.js. To disable hardware acceleration, I scrolled down to:

user_pref("layers.acceleration.disabled", false);

and changed "false" to "true". I then save dthe file, and re-opened SeaMonkey. Presto! VNC control.

For the curious, run a web search on the pref name. I have yet to find a complete, up-to-date guide on Mozilla prefs, but there are a number of hits available to help fill in the gaps until MozillaZine catches up.

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