I've heard from several of my customers that have upgraded to Visual Studio 2008 that they've been unable to access custom controls on the toolbox. It doesn't matter whether the controls were auto-installed or manually added. According to several of the customers the controls simply show greyed out and apparently disabled so that they can't be accessed. You can't access the controls on the toolbox although standard controls work just fine.
It turns out that the cause is: Interaction with certain mice. Specifically Microsoft Laser Mice which have for some reason been a major problem with Visual Studio now and in the past. It's ironic that Microsoft mice specifically should have these problems, but apparently there's an issue with the drivers (or the generic HID driver they also use) that affect the idle timing that the ASP.NET designer relies on.
It's not just with my controls and tools though. Here's a thread on the ASP.NET forums that talks about the same issue with the AJAX Control Toolkit:
http://tinyurl.com/35zayz (cached the original url doesn't appear to work anymore)
Sure enough after I found the above thread I mentioned to several of our customers that were seeing these problems to unplug their mice and immediately the controls showed up properly in the ASP.NET designer toolbox.
Can Microsoft EVER get this right?
This is really a sad state of affairs. I've had lots of problems in the past related to this same sort of idle time detection in Visual Studio, but it's always been in the ASP.NET designer, never with any of the other tools. In the past it's affected Intellisense activation, property sheet synching issues and now this odd toolbox behavior. And FWIW this problem has apparently not been solved by the recent HotFix Microsoft released specifically to address a host of ASP.NET designer issues in Visual Studio 2008.
There are a few things that you can do to minimize these mouse related problems. On Vista make sure that you install the latest mouse drivers and if you haven't done so install the latest HID driver. Windows Update should have updated the HID driver automatically last year and it fixed a host of weird issues for me at the time in Visual Studio 2005. If for some reason you're not installing updates check for that one at least and install it. The latest mouse drivers from Microsoft also should include the latest HID driver. Personally I do not have the Control Toolbox issue, so it must be a specific hardware/software combination that's making this happen, but given that I've heard from roughly a dozen customers this is not an isolated problem. According to the above thread too it doesn't seem to be a rare instance and there are certainly a lot of Microsoft Laser Mice out there.
I hope the ASP.NET Visual Studio Web Tools team can take a closer look at these issues that keep cropping up over and over again. I've been struggling with lagging focus and activation issues in the ASP.NET designer and in many cases - all the way back to Visual Studio 2005 - the issues were always caused by the mouse. Unplugging the mouse and using the mouse pad often completely solved the problems. It seems to me that there's a serious flaw in the assumptions that the ASP.NET designer makes to detect idle state (or whatever it does to refresh the UI) and it's only a problem in the ASP.NETdesigner. None of the other tools in Visual Studio have had any of these issues so there's gotta be a better way to deal with this than tie designer refresh operations to whatever particular idle state is used at the moment.
As a side note, it seems harder and harder to be able to get a decent WIRED mouse these days. I've thought about using a different mouse but I've become hopelessly attached to my smallish Microsoft Wireless Laptop mouse. Wireless mice are nice but they can get funky if there's interference or line of sight blockage. I would go back to a wired mouse if only I could find a decent small one for my girlish sausage fingers <g>...