EntryPointNotFoundException when using TaskDialog in C#.

Question

I'm using the following code to call a TaskDialog.

    [DllImport("ComCtl32", CharSet = CharSet.Unicode, PreserveSig = false)]
    internal static extern void TaskDialogIndirect(
        [In] ref TASKDIALOGCONFIG pTaskConfig,
        [Out] out int pnButton,
        [Out] out int pnRadioButton,
        [Out] out bool pfVerificationFlagChecked);

However, I get the exception "Unable to find an entry point named 'TaskDialogIndirect' in DLL 'ComCtl32'."

I took this code. I am using Windows 7 x64 (RC).

What am I doing wrong?

Answer 1

Nothing except this is a vista feature

UPDATE: This probem had to do with side by side assemblies: these functions are present only in comctl32.dll version 6, but, for compatibility reasons, Vista will load an earlier version unless you tell it otherwise. The approach most people (including me) have been taking is to use a manifest. This has proven to be tricky, and may not be the right solution anyway, especially if what you're writing is a library: you don't necessarily want to force the entire application to use common controls 6.

The right solution is to push a new activation context when calling one of the Vista-only APIs. The activation context will use the correct version of comctl32.dll while leaving the rest of the application alone, and no manifest is required.

Fortunately, this is easy to do.Some complete code that already exists MS Knowledgebase. The code from the article (KB 830033) does the trick as is.

Alternative Managed API: A full wrapper for Vista's TaskDialog & TaskDialogIndirect can be found here:

http://code.msdn.microsoft.com/WindowsAPICodePack

For WPF use the following:

Download the 'VistaBridge Sample Library' from http://code.msdn.microsoft.com/VistaBridge once downloaded, open the project and then build it (if you want to look through all the code, examine the files in the \Library or \Interop folders). You can now take the DLL from VistaBridge\bin\debug\ and add a reference to it in your project, as well you must add a using statement for each of the different VistaBridge modules. For Example:

using Microsoft.SDK.Samples.VistaBridge.Interop or .Library or .Properties or .Services - Depending on your needs.

The VistaBridge project includes API's for many other Vista Features (such as the TaskDialog, Vista OpenFile and SaveFile Dialogs, and of course the Aero Glass Effects) to try these out, run the VistaBridge Project.