vis: add workaround for broken color handling in Terminal.app

Terminal.app sets $TERM=xterm-256color and ships a corresponding
terminfo description advocating that it is capable of color changes
to the 256 color palette when in fact it can not.

We introduce a new boolean option "change-256colors" which is
true by default but can be used to disable color changes. It is
automatically set if Terminal.app is detected using $TERM_PROGRAM.

This should fix display artifacts as described in #456.

1 files changed, 3 insertions, 0 deletions

diff --git a/vis-cmds.c b/vis-cmds.c
index 879eadd..8e512cc 100644
--- a/vis-cmds.c
+++ b/vis-cmds.c
@@ -291,6 +291,9 @@ static bool cmd_set(Vis *vis, Win *win, Command *cmd, const char *argv[], Cursor
 			return false;
 		}
 		break;
+	case OPTION_CHANGE_256COLORS:
+		vis->change_colors = toggle ? !vis->change_colors : arg.b;
+		break;
 	default:
 		return false;
 	}