CODEWITHSUNDEEP
.netwinformsmodal-dialog
Scott Hagie
Scott Hagie

Reputation: 33

How do I stop form.showdialog from locking a grandparent form in DotNet?

So I have a menu form for my application, let us call it the grandparent. The user clicks a button, and it calls another form, let's call it the parent form, with form.show(). Because I used show(), and not showdialog(), I can play around with either form now.

Then, in the parent form, I call a third form, let's call it child, with a form.showdialog(). I want the user to have to close the child form before being able to do anything with the parent form, and that is exactly what happens. The problem is that now I can't use the grandparent form either, it is locked until I close the child form, and I don't want it to be.

In other words, I want the child form to be modal, but only in respect the parent form, not the grandparent form. Can such a thing be done?

Upvotes: 3

Views: 2334

Answers (2)

DarkSquirrel42
DarkSquirrel42

Reputation: 10257

if you can live with the fact that your parent and child forms live on another thread than you grandparent (so you will have to invoke when you need to use controls on the other thread) you could start a 2nd UI thread for your parent form ...

when the modal dialog blocks the message queue of the parent forms UI thread, the grandparents UI thread will still have its own non-blocked message queue ...

so instead of calling 

new ParentForm().Show();

somewhere in the code of your grandparent-form call

new System.Threading.Thread(
                    delegate() {
                        Application.Run(new ParentForm());
                    }
                ).Start();

Upvotes: 3

Igby Largeman
Igby Largeman

Reputation: 16747

ShowDialog() blocks the UI thread, so I don't think it can be done easily. You could launch the child form in a new process... but that's pretty drastic.

You could disable the parent form manually (disable all controls - put everything on a UserControl or a Panel and just disable that). Then you could just throw up a message if the user happens to click on the parent form, saying "please close first". When the child form closes, re-enable the parent.

If you want to make sure the child form stays visible, set the TopMost property, but be wary of doing that since it can really annoy the user.

Upvotes: 0

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