Add per-window resize-margin override (Hyprland's extend_border_grab_area)

MISSING.md had listed this as needing to touch srdwm_core::window::
hit_test's signature at every call site, including the honest-stub
Windows/macOS backends - overstated on closer inspection: that shared
function already takes a plain resize_margin: i32 parameter, agnostic
to where the value comes from. The only real change needed was reading
Window.resize_margin.unwrap_or(wm-wide default) instead of always the
WM-wide value, at the single call site inside WindowManager::hit_test
in core - no backend touched at all.

Window.resize_margin: Option<i32>, WindowRuleActions.resize_margin to
match, applied in add_window/reapply_rules_if_pending the same way
opacity already is. Settable via a rule action or
srd.window.set_resize_margin(n) on the focused window.

1 files changed, 14 insertions, 0 deletions

diff --git a/crates/config/src/engine/window.rs b/crates/config/src/engine/window.rs
index 6193f81..a7e6bf3 100644
--- a/crates/config/src/engine/window.rs
+++ b/crates/config/src/engine/window.rs
@@ -153,6 +153,20 @@ impl Engine {
         })?)
     }
 
+    pub(super) fn fn_window_set_resize_margin(&self) -> Result<mlua::Function<'_>> {
+        let state = self.state.clone();
+        Ok(self.lua.create_function(move |_, margin: i32| {
+            let wm = state.borrow().wm.clone();
+            let mut wm = wm.borrow_mut();
+            if let Some(id) = wm.focused_id() {
+                if let Some(w) = wm.window_mut(id) {
+                    w.resize_margin = Some(margin);
+                }
+            }
+            Ok(())
+        })?)
+    }
+
     pub(super) fn fn_window_set_floating(&self) -> Result<mlua::Function<'_>> {
         let state = self.state.clone();
         Ok(self.lua.create_function(move |_, floating: bool| {