Drawing Straight Lines without Grid

Been loving the dynamic lighting ever since I started using it a few months ago, but something has eluded me. When drawing my maps, and using the line tool, I would like to be able to snap to the 0, 45, 90 , 90   angles etc, rather than to the grid. For areas of my maps that may not align with the grid. Is this possible?

Can you turn on the grid to do your drawings, then turn the grid off when you are done?

Yes, the problem is walls and such on my maps, where there would be an angle or secret door etc, dont always line up with the grid, even with the grid perfectly aligned there are variances that cause it to not line up. usually off by like 10pixels are so, perhaps ill just try lining my walls up better so the grid falls in the center of a share wall, and not on the edge of one room.

This Innovative Trick  by Ziechael might be useful for what you want to do. I use this to get DL lines that are half a grid space away from exterior walls (so that players see more than just a wall line, but they still can't pass through them) by changing the grid to .5 while setting the lines (then setting the grid back to 1 for play).  But I've also used it before at .25 or .1 to get more fine tuned 'drawn' lines.