Created attachment 112142 [details]
Demonstration of 45 degree lines

Steps to reproduce:
1. Use "Pixel Brush" and the Line Tool.
2. Click and hold. Then hold shift and drag out a 45 degree angle.
3. Release.

Actual Results:
The resulting line tends to have random jaggies along the line. (See the attached example.) On rare occasions the line is perfect, though I haven't been able to nail down exactly what triggers this.

Expected Results:
Neat corner-to-corner pixels making up a line.