How to draw path so it snaps to edges and how do I make tabs overlap?

See picture. This is tab design I'm working on for my TabControl:

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As you see - path got 4 points - corners of my tab. But no matter how I try - with enough magnification I see some kind of artifacts when running. It seems that top and bottom not parallel and I'm not sure how to make it "snap" to grid edges. Anyone?

Also, this Grid around my Path is actually TemplateTopSelected which is part of TabControl's template.

What do I need to do to make tabs overlap like so (and on a bottom see what I have):

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Solution

There are a couple of ways to align paths to grid.

First, you can enable a snap grid for the artboard. This is done in Tools\Options menu.

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Now when you add a point to a Path it will snap to the nearest grid point. To enable/disable this setting quickly (once you've configured the grid) you can use the snapping button on the bottom of the artboard.

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Shift-Click

Another tip is to hold down the Shift key when drawing the path. This contrains the point placement to to 45 degree angles. This works whether you have grid snapping enabled or not.

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