I have a VirtualMode DataGridView that bogs down on using the mouse wheel to scroll and gets a backlog of messages such that it continues to scroll long after ceasing to turn the mouse wheel. This is because instead of generating one scrollbar message for each mouse wheel message it generates a separate scrollbar message for each line move, forcing the entire screen to refresh with each line added.

I've put in code to scroll multiple lines only once for each mouse wheel click, but I'm still having to shunt out all of the extra scrollbar messages and it is not easy. If I get out of sync as to how many scrollbar messages to shunt the scrolling goes out of whack. It would be far easier if I just didn't have to worry about shunting these useless messages.

So how do you prevent mouse wheel messages from creating scrollbar messages?

Just shooting from the hip here, but have you tried the .Handled statement in the mousewheel event procedure to eliminate further bubbling up (through the scrollbar event handler, for instance) of the messages?

There is no Handled member of the MouseEventArgs class. You had me really excited there for a moment!

Do you think it might be possible to add something useful to the MouseWheel()'s "Handles" list the additional events so that all comers come to the same routine? (I don't really have a candidate in mind.)

Perhaps you could then use a global boolean to block re-entrance into that procedure until the time of your choosing. Perhaps that will allow you to put the brakes on just a little, and that will be enough.

I didn't realize that .handled was kind of limited to key events... Sorry.

Looks like I have a couple of options, derive my own DataGridView and override the WndProc function, or check the sender in the grid's scroll handler and shunt the extra scroll messages manually.