12.2. Frame Style
As with all widgets, you can use the -relief and -borderwidth options to change how the edges of a frame widget are drawn. The default -relief is 'flat', and the default -borderwidth is 0. If you want the frame to have any edges at all, make sure you change -borderwidth to something higher than 0. Unless you put something in a frame, you'll never see it. So, for the examples in Figure 12.1, I have inserted a label widget and an entry widget that state the relief of that frame. Note that I actually created a label widget by using Label() and did not use the -label option (see the next section).
Figure 12.1. Different relief values for frames; borderwidth of 2 and borderwidth of 5

Using -relief and -borderwidth is a great way to find out where your frame is in the window. If you have a complicated window, it's confusing to remember which frame is where. I'll often add -borderwidth => 5, -relief => "groove" to my Frame command to find that frame in the window.
12.2.1. Adding a Label to a Frame
With Perl/Tk, you can add a label to your frame by using the -label option, which takes a text string as an argument:
$mw->Frame(-label => "My Frame:")->pack; ... # configure label in frame later : $frame->configure(-label => "My Frame:")->pack;
By default, the label is placed at the top of the frame, centered across the width (see Figure 12.2). Again, I put something in ...