Treat major and minor ticks differently (in GR, for now)

[greimel]

I am working on a theme that resembles the default theme of ggplot2 (JuliaPlots/PlotThemes.jl/pull/30).

The goal is this:

Note that ggplot2 doesn't show ticks for minor grid lines. This is not currently possible in plots.

The first commit partly solves the problem for gr().

I compute the minor grids separately and assign them the color of the border. This would in principle solve my problem. However, I do not like this fix yet. I would like to add a new attribute foreground_color_minor_ticks or similar to set this color. I tried to do this, but got an error that I do not understand. Unfortunately I know too little about Plots.jl.

Could someone look at my last commit and guide me a bit in proceeding here?

PS: I propose to introduce an attribute foreground_color_major_ticks as well. It's not yet clear to me what the exact purpose of foreground_color_axis and foreground_color_border are (see my previous PR #1787)

[greimel]

plot(rand(10), rand(10), foreground_color_tick = :green, foreground_color_minortick=:red, minorgrid=true)

As laid out in #1794 I could delete the foreground_color_axis attribute and replace it by foreground_color_tick in all backends--if you think that this is a good idea.

[daschw]

I would add these to _match_map instead and let them default to :foreground_color_axis (which then defaults to :foreground_color_subplot). Then you should be able to have different tick colors for different axis.

[mkborregaard]

hey @greimel would you mind doing this minor change so we can get this merged? Thanks!

[greimel]

Sorry for not finishing this PR. I've not used Plots.jl for a year or two. Please feel free to take the code or close the PR.

[BeastyBlacksmith]

It was decided in the last maintainer call (#3538) that rebasing this PR is not worth the effort and that we'd need a reimplementation of this on the current state of Plots.

[isentropic]

Totally missed this maintainers' call, is there a reminder thread or something? @BeastyBlacksmith

[BeastyBlacksmith]

You should have got an email. If not hit me on zulip.