How to use MouseWheel to scroll MDI parent window in Winforms app

StackOverflow https://stackoverflow.com/questions/977014

  •  13-09-2019
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Question

I have a VB.Net Winforms app which displays an MDI parent form and allows multiple child forms to be displayed on it. If the child forms extend beyond the screen height, a vertical scrollbar is automatically displayed on the right side of the MDI Parent & I can use this scrollbar to scroll the child forms into view.

But, the mousewheel has no effect on this scrollbar. How can I make the mousewheel scroll the child forms?

I can handle mousewheel events, but I am not sure what to do with them once I handle them to enable scrolling of the window.

Was it helpful?

Solution

Once you capture the mousewheel event, simply call SetDisplayRectLocation() of the control being scrolled. Something like

myControl.SetDisplayRectLocation(
            myControl.DisplayRectangle.X, 
            myControl.DisplayRectangle.Y + MouseWheelDelta * ScrollAmount
          );

(ScrollAmount is a constant you define -- start with 30 pixels).

You also need to call AdjustFormScrollbars() on the main form as well to update the scroll bar location.

(Sorry, that's C# -- I don't know VB syntax)

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