I customized my geany message window compiler tab via ~/.config/geany.css on a fedora 27 system:
treeview {
background-color: #2e3436;
color: #dfdee0;
}
treeview:selected {
background-color: #626d71;
}
/*#geany-compiler-error {
color: red;
}*/
#geany-compiler-message {
color: #dfdee0;
}
#geany-compiler-context {
color: orange;
}
It's working well unless I
select a line of a compiler error or a compiler context. Then line color switches to the color I set for treeview nodes in general in the first rule.