For the strokes drawn using OpenGL lines, moderately-sized changes in the pressure between two points could result in the stroke being disjointed, since a new GL_LINE_STRIP would need to be created with the new line thickness due to the new pressure value. (In reference to the summary of this commit, this bug was noticed by Matt Ebb (broken). This bug is also in 2.4x, but was suprisingly not really noticed.)