Just to better understand the owner-owned relationship:
.NET allows a form to “own” other forms. Owned forms are useful for
floating toolbox and command windows. One example of an owned form is
the Find and Replace window in Microsoft Word. When an owner window is
minimized, the owned forms are also minimized automatically. When an
owned form overlaps its owner, it is always displayed on top.
(c) "Pro .NET 2.0 Windows Forms and Custom Controls" by Matthew MacDonald.
As ShowDialog shows the new form, an implicit relationship is
established between the currently active form, known as the owner
form, and the new form, known as the owned form. This relationship
ensures that the owned form is the active form and is always shown on
top of the owner form.
One feature of this relationship is that the owned form affects the
behavior of its owner form (when using ShowDialog):
- The owner form cannot be minimized, maximized, or even moved.
- The owned form blocks mouse and keyboard input to the owner form.
- The owner form is minimized when the owned form is.
- Only the owned form can be closed.
- If both owner and owned forms are minimized and if the user presses Alt+Tab to switch to the owned form, the owned form is activated.
Unlike the ShowDialog method, however, a call to the Show method does
not establish an implicit owner-owned relationship. This means that
either form can be the currently active form.
Without an implicit owner-owned relationship, owner and owned forms
alike can be minimized, maximized, or moved. If the user closes any
form other than the main form, the most recently active form is
reactivated.
Although ShowDialog establishes an implicit owner-owned relationship,
there is no built-in way for the owned form to call back to or query
the form that opened it. In the modeless case, you can set the new
form's Owner property to establish the owner-owned relationship. As a
shortcut, you could pass the owner form as an argument to an overload
of the Show method, which also takes an IWin32Window parameter
(IWin32Window is implemented by Windows Forms UI objects that expose a
Win32 HWND property via the IWin32Window.Handle property).
The behavior of forms in an explicit modal owner-owned form
relationship is the same as its implicit modal counterpart, but the
modeless owner-owned relationship provides additional behavior in the
non-owner-owned modeless case. First, the modeless owned form always
appears on top of the owner form, even though either can be active.
This is useful when you need to keep a form, such as a floating tool
window, on top of other forms within an application. Second, if the
user presses Alt+Tab to switch from the owner, the owned forms follow
suit. To ensure that the user knows which form is the main form,
minimizing the owner hides the task bar buttons for all owned forms,
leaving only the owner's task bar button visible.
(c) "Windows Forms 2.0 Programming" by Chris Sells, Michael Weinhardt.
