C#: Synchronize Scroll Position of two RichTextBoxes?

Question

In my application\'s form, I have two RichTextBox objects. They will both always have the same number of lines of text. I would like to \"synchronize\" the vert

Answer 1

[Visual Studio C# 2010 Express, v10.0.30319 on a Windows 7 64bit installation]

I've used Donut's solution posted above, but found a problem when scrolling to the end of RichTextBoxes that contain many lines.

If the result of GetScrollPos() is >0x7FFF then when nPos is shifted, the top bit is set. The creation of the IntPtr with the resulting wParam variable will then fail with an OverflowException. You can easily test this with the following (the second line will fail):

    IntPtr ip = new IntPtr(0x7FFF0000);
    IntPtr ip2 = new IntPtr(0x80000000);

A version of SendMessage() that uses UIntPtr would appear to be a solution, but I couldn't get that to work. So, I've use the following:

    [DllImport("User32.dll")]
    public extern static int SendMessage(IntPtr hWnd, uint msg, UInt32 wParam, UInt32 lParam);

This should be good up to 0xffff, but would fail after that. I've not yet experienced a >0xffff result from GetScrollPos(), and assume that User32.dll is unlikely to have a 64bit version of SendCommand(), but any solutions to that problem would be greatly appreciated.