config: add keyboard-focus window criteria

src/criteria/tlm/tlm_matchers/tlmm_seat_focus.rs

@@ -0,0 +1,28 @@
+use crate::{
+    criteria::{
+        crit_graph::CritRootCriterion,
+        tlm::{RootMatchers, TlmRootMatcherMap},
+    },
+    ifs::wl_seat::SeatId,
+    tree::ToplevelData,
+};
+
+pub struct TlmMatchSeatFocus {
+    id: SeatId,
+}
+
+impl TlmMatchSeatFocus {
+    pub fn new(id: SeatId) -> TlmMatchSeatFocus {
+        Self { id }
+    }
+}
+
+impl CritRootCriterion<ToplevelData> for TlmMatchSeatFocus {
+    fn matches(&self, data: &ToplevelData) -> bool {
+        data.seat_foci.contains(&self.id)
+    }
+
+    fn nodes(roots: &RootMatchers) -> Option<&TlmRootMatcherMap<Self>> {
+        Some(&roots.seat_foci)
+    }
+}