Comment 13 for bug 1357611

If the alpha is set for dots as it is set for lines, the dots become barely visible. To maintain a similar visual impact the alpha for dots needs to be increased, but as pointed out here, setting it to its maximal value can be too much.

I've patched the code to increase the alpha when using dots by a factor of four (of course, clamped by full opacity). This seems to give a similar visual impact but still allows a user to lower the alpha if needed.

The alpha treatment for dot/cross was/is simply to emphasize the major grid points.