I recently got a call from a student who was having a big problem drawing lines with the Line tool (\). He clicked-and-dragged with the Line tool and as soon as he deselected his newly-drawn line (Command + Shift + A [Control + Shift + A on PC]), it disappeared from his layout. What was this about? Was it a bug?
No, it’s actually a default combined with an InDesign oddity. The Default Stroke for the Line tool is None, as it is for all drawing tools (object creation tools) in InDesign. You could change this default for the application by clicking on the Line tool and adding a black, or any other color stroke with no documents open. But this would also change the default for ALL drawing tools, except for Frames (containers for images or type). This, in my opinion, is far less of a problem than a previously mentioned InDesign oddity. Open paths (other than Frames) that have no Stroke and Fill, including objects drawn with Line, Pencil, and Pen tools, cannot be seen when they are not selected. Finding these invisible paths is not easy. It takes a lucky click with the Selection tool or the Select All command (Command + A [Control + A on PC]). To me, changing the default to a black stroke seems to be a far better option.
Tip provided by Jeff Witchel, Certified Adobe® Training Provider.