How can I sync the scrolling of two multiline textboxes?

Question

How can I sync the scrolling of two multiline textboxes in C# (WinForms)?

When you scroll up/down a line in TextBox A, TextBox B should scroll up/down too. The same

Answer 1

Hans Passant's solution worked like a charm but I needed a RichTextBox with both horizontal and vertical scrollbars. If you extend a RichTextBox instead of a TextBox you'll need to change the ScrollBars property accordingly (I used RichTextBoxScrollBars.Both).

If you want to sync horizontal scrolling as well, look for (m.Msg == 0x115) || (m.Msg == 0x114).