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How Do I check if an MDI Child window has Focus?

rangers99 asked
Medium Priority
Last Modified: 2012-05-06
I thought you could just use the Focused property ie.

if (win1.Focused)
  // do something

But this aint working. Whats the right method to use? Thanks.
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The following works for me.

Myform t = new MForm();
t.MdiParent = this;
This is in the code for my Parent Form.  Where is the code you are running?


Hi Dave
What Im doing is selecting a window then clicking a menu item which has the following code. Ive traced  it through and the Focused property is never set to true. Its always false. Id have thought clickin on a child window would have set the focused property.

 for (int i = 0; i < this.MdiChildren.Length; i++) {
                    if (this.MdiChildren[i] is TRResultWindow) {
                        if (this.MdiChildren[i].Focused) {

                            i = this.MdiChildren.Length;
Hmm so if the Focused property isn;t working mayeb you can manually set it when the form received focus unless it is read only in which case you couuld add your own property and set that when the window receives focus and unset it when the window loses focus?
A bit hacky but might be worth a go.


Yeah it looks like the focused property is broken. Still I cant beleive I have to do a hack for something as fundamental as this. I see there is a TopMost property. This may work but is it automatically true that a window that has been clicked on by the user is the topmost window?
Hmm not sure, sounds likeley but maybe there are some weird sceanrios where this wouldn't be the case?
Hi Dave

Ive solved it.

'ContainsFocus' works. Ive no idea what Focused does. Its a bit confusing.

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Mike TomlinsonHigh School Computer Science, Computer Applications, Digital Design, and Mathematics Teacher
Top Expert 2009

Try it this way?

    if (this.ActiveMdiChild is TRResultWindow)
        // do something in here...

See: http://msdn.microsoft.com/en-us/library/system.windows.forms.form.activemdichild.aspx
Ok cool as long as it's working that's the main thing.


if(this.ActiveMdiChild == childForm)
     //Your work


Hi guys

Thanks for the extra comments but I got it to work fine using the "ContainsFocus" property.
Im not sure what the procedure is to close a question, it would save you time trying to solve a problem for me that Ive already solved.
If youve fixed a question yourself you should click delete question button at the top and then I think you have an option to accept your own answer as the solution.
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