When using a 4:3 resolution your pickaxe and other tools appear in the center of the screen instead of in the right hand, causing them to appear to swing off screen to the left. You can marginally work around this by hiding hand.

This is just my educated guess but... It should be fixed to show the tool within a certain % of the horizontal resolution rather than by a fixed unit count from the edge of the screen.

Current Game Resolution is 1280x1024