How can I make a dialog window appear in front of all other open windows?

I'm writing a photo-editor, and I have two figures open. One has the original image and one has the modified image. This is very, very simple, and it's just a homework assignment, so I'm not worried about making a good manipulator.

When the user selects an option from the menu though, I want to pop up a help dialog with some explanations of the feature. However, when I do this, the help dialog gets hidden behind the input dialog that I open on the next line of code. It also gets hidden behind the second figure.

Is there something I can do to prevent this?

This is my first post, and I'm reading the tips above the editor, and it says to include code to reproduce the problem. Realistically, I'd have to give you the entire program, along with the images in order to replicate this. Would this help?

Hopefully the description is good enough. It seems like the solution should be something very simple, but I just don't know what it is.

Thanks!