Newbie constraint question

[raduray]

Simple newbie question:   I want to place a rail on a panel and need to constrain the front of the rail to the edge of the panel.  I first sketch and extrude the panel.  Then I sketch the rail on the surface of the panel.  If I sketch the rail in the correct position, with the front of the rail rectangle against the front of the panel, I am not able to select the two collinear edges as they overlap.  However, when I draw the rail so that it's offset from the desired location, I can then use the collinear constraint tool to select the edge of the panel and the front of the rail and Fusion 360 then moves the rail to the correct position.  Is there any way to use the constraint tool when the two edges are on top of each other, or do I have to offset them when sketching them so that I can easily see and select the desired lines?

Hope this makes sense.  

[laughingcreek · Accepted solution]

long mouse button click over sketch object brings up list of everything under cursor.  select the shorter line from list.

or possibly better, don't use rectangle for the rail profile.  just draw the three other lines to complete the profile.  it's a good idea to avoid layering sketch object exactly on each other where they are hard to find.

[raduray]

So if I want to lay out a new rectangle with one side collinear to an existing rectangle, I draw the three non-collinear lines/sides and the collinear line/side is then implied?  I tried it and it worked and was able to extrude the new rectangle as a separate component.  Neat!  Thanks!

Is this described in more detail somewhere?