Child Windows

There is an excellent example project named child_windows included with visualruby. To try it, click on the Open Project button.

Child windows are simply windows that you open from your main program.

There are 2 types of windows you can use:

  1. Modal Windows – Windows that halt the main program until they are closed.

  2. Modeless Windows – Windows that operate simultaniously with their parent.

You can select which type of window to use in glade:

Just check or un-check the Modal checkbox to set which type of window you prefer.

The type of window that you open will depend on the situation:

Modal Windows

The benefit of using modal windows is that they will halt your program's execution until they're closed. This behavior is often desireable when you don't want users to be able to make any changes while the child window is open. A good example of this is visualruby's alert box:

The program will insist on getting an answer from the user before doing anything.

Also, you should always set a parent window for all modal child windows so the child will always appear on top of the parent window. This is always desirable behavior because you don't want to allow the parent to appear on top of the child while the parent is frozen. If the parent window hides the child window, the user will be confused because the parent will not respond to mouse clicks until the child is closed. Therefore, make sure to set a parent window for all modal child windows so the user always sees the child that is insisting on a response.

To create a modal child window, set its Modal property to true in glade (see above). Then simply open it using code:

win =
win.show_glade(self)  # self = parent window

Here, the reference to self makes the child window always appear on top of the window, self.

Modeless Windows

Modeless Windows are simply windows that function simultaneously with the main window. An example of modeless windows is a word processor where you want to have several open documents that function independently from each other, and you are free to switch between them.

To open a modeless window, simply un-check the Modal property in glade (see above), and open it normally. The window will function along side to the main program.

Usually, you don't want to set a parent window for a modeless window because you want to allow the user to bring the main window to the top, and have the child appear behind it.

So the code to open a modeless window looks like this:

win =

Note that the #show_glade method doesn't pass a parent window, so either window can appear on top.

Returning a Value From a Modal Window

One of the benefits of modal child windows is that your main program can wait until the child window returns a value. This can make them function like dialog boxes.

When you halt the parent window you can return a value from the child window to the parent:

@value = nil
win =  # ChildWindow is a class you define.
win.show_glade(self)  # program halts.  Sets value of @value
if @value = "Value Now Set!" then
   ...your code here

The ChildWindow class sets the value of @value before closing:

class ChildWindow
   def initialize(parent)
     @parent = parent

   def buttonSave__clicked(*a)
     @parent.value = "Value Now Set!"

So, when the user clicks the buttonSave button, it sets the @value variable that your program can respond to. This is how visualruby's #alert method works. It freezes the main program, and returns the value from the user.

Modeless Window With Parent

Rarely, you may want to open a modeless window that functions simultaneously with the main program, but always appears on top of it. An example of this behavior would be a “Search and Replace” window in a text editor where you want the ability to edit the text in the editor without the “Search and Replace” window disappearing behind the editor window.

To acheive this behavior, simply set the Modal property to true (checked) and pass a reference to the parent to the #show_glade method:

search_replace_win =
search_replace_win.show_glade(self)  # self = parent window

Now the search_replace_win window will always be on top of the self window.