mango: show focused window next to tags, fix mmsg lookup, 0.15.x compat

- new focused-window block ({icon} {app_id} - {title}) driven by the
  active_client field of mmsg watch all-monitors (mangowm >= 0.14)
- resolve program icons via freedesktop icon themes/.desktop files
  (new icon module, cairo png feature, cached per app_id)
- new show_focused_window config option (default true)
- run mmsg from PATH instead of hardcoded /usr/bin/mmsg (broken on NixOS)
- handle null active_client fields (no focused client) without failing
  to parse the whole event
- drop stale TODO comment and unused variable in mango provider
- add .justfile run recipe exporting MANGO_INSTANCE_SIGNATURE

1 files changed, 9 insertions, 0 deletions

diff --git a/src/wm_info_provider.rs b/src/wm_info_provider.rs
index d598234..67e5f83 100644
--- a/src/wm_info_provider.rs
+++ b/src/wm_info_provider.rs
@@ -47,6 +47,9 @@ pub trait WmInfoProvider: Any {
     fn get_mode_name(&self, _: &Output) -> Option<String> {
         None
     }
+    fn get_focused_window(&self, _: &Output) -> Option<FocusedWindow> {
+        None
+    }
 
     fn click_on_tag(
         &mut self,
@@ -83,6 +86,12 @@ pub fn bind(conn: &mut Connection<State>, config: &WmConfig) -> Box<dyn WmInfoPr
     Box::new(DummyInfoProvider)
 }
 
+#[derive(Debug, Clone, PartialEq)]
+pub struct FocusedWindow {
+    pub app_id: String,
+    pub title: String,
+}
+
 #[derive(Debug)]
 pub struct Tag {
     pub id: u32,