Change message WParam and LParam properties to IntPtr for x64 support

[pziezio]

Hello,
First, I'd like to thank you for your library. I've been using it for some time with great success.

Recently I changed all of my WinForms applications to 64-bit versions.
After that TaskDialogs stopped working.
Showing of a simple dialog still works, but you can't change any of the properties of a dialog that is already shown. Application is failing with System.OverflowException.

I tracked the problem to windows message loop procedure and message class itself.
Currently Message class has WParam and LParam properties defined as int (32bit) and that is causing problems.

Setting a new property value actually sends new windows message, so for example:
There is a Message class constructor that takes string as a parameter.
It uses Marshal runtime to get a pointer (IntPtr) to character data and it tries to assing that value to LParam - which is 32bit int. That results in an overflow exception.

It seems that the problem is easily solved by changing type of WParam and LParam properties to IntPtr - a type whose size is platform dependent, just like the underlying WPARAM and LPARAM types from WinAPI.

Please take a look at the following changes that I made:
https://github.com/pziezio/WindowsFormsAero/commit/0a4cef194d40760f58e10427e1bb8b41c5b0d854#diff-3d7d9b2fdd0df5be3ed6890538248201

I could submit a pull request for this change, but I don't have any experience with creating configuration for multi-platform NuGet packages and I don't know how a new package configuration should look.

Best regards
Piotr Zięzio

[LorenzCK]

Hello @pziezio,
sorry for the late reply, thank you for the heads up and for the detailed explanation: the issue should now be fixed. I included the suggested changes in this commit (which preserves the authorship of your suggestions).
I'll try to pack up the changes in a NuGet update as soon as possible.

Thanks again!