问题
I presume a winform's owner can be set explicitly via the .Owner property OR by passing the owner in the overloaded method ShowDialog(IWin32Window owner)
I am unable to understand why these methods exhibit different behavior when working with MDI forms.
I have created an MDIParent and an MDIChild.
I also have a simple winform MyDialogBox that displays its owner on load.
MessageBox.Show("Dialog's owner is " + this.Owner.Name);
Method A - In the load of MDIChild I have the following code, which causes the MyDialogBox's owner to be set to MDIChild
MyDialogBox box = new MyDialogBox();
box.Owner = this; // Set owner as MDIChild
box.ShowDialog();
Method B - Alternatively, in the load method of MDIChild I have the following code, which causes the MyDialogBox's owner to be set to MDIParent
MyDialogBox box = new MyDialogBox();
box.ShowDialog(this); // Pass MyMDIChild as owner
I also read the following here
Only the MDI parent form can own another form, be it a MDI child, a modal dialog or a form where the parent was set as the Owner param.
If so Method A should not work at all, isn't it ?
What am I missing? Why doesn't method B set the owner to MDIChild ?
回答1:
Looking at the differences of these 2 options using Reflector, it seems that they have a slightly different implementation:
box.Owner = this just assign the provided value of this to the internal owner field.
However, when calling ShowDialog(IWin32Window), the implementation performs the following call, prior to assigning the value:
owner = ((Control) owner).TopLevelControlInternal;
This might result in assignment of the MDIParent.
(Note: I'm far from being an expert regarding MDI, so I might be wrong here).
来源：https://stackoverflow.com/questions/395186/difference-between-owner-property-and-showdialogiwin32window-owner