Not yet, at least not on the layout itself. You can draw a line on the Canvas object, though.
Hmm, found a weird bug:
When choosing a line color to draw in the action, it won't remember expressions. I can type in an expression (like 157 or random(255255255.0)) and when I go back into the action to edit it, it's reverted to the "Default" color picker, and the chosen color is black.
Also, check out this example:
It's supposed to draw a line of random color from 0,0 to Sprite.X, Sprite.Y (controlled by the mouse. For some reason it wouldn't draw to MouseX, MouseY.) Instead of a random color, though, it draws only black... unless you move the mouse outside of the window. Then you see it flashing to random colors.
Another thing, if you turn of "Grab Frame" and move the mouse outside of the window, the line still stays black, but "fades out" as it gets toward the edge of the window.
Bug submitted to SourceForge