Adds glue that connects two controls together. For example, if you've just added a label and want to ensure the textbox you're adding next is always next to the label, add glue between adding the label and adding the textbox. In this way, if you resize the control such that the textbox doesn't fit on the line, both the label and the textbox will move to the next line together. This must be called immediatly after adding the label. The next control to be added will be the control the label is glued to.
