Highclip issue when changing it

[asinghvi17]

using Makie
using GLMakie

hc = Observable{Any}(:red)
lc = Observable{Any}(:blue)
f, a, p = heatmap(rand(10, 10); highclip = hc, lowclip = lc, colorrange = (0.25, 0.75))
p.highclip # Observable{Any}
hc[] = nothing # error
p.highclip[] = nothing # error

this is because the lift was having issues. Have patched this locally and will push it up to a PR.

It works with Cairo, but GL backends will still have issues. Set the high/low clip to be the first and last of to_colormap(plot.colormap[]) in order to get around this while maintaining the desired behaviour.

[ffreyer]

This doesn't error anymore but the updates aren't tracked in GLMakie so it doesn't produce a different image until something else triggers an update.