wf-kill: cancel a pending selection when the output is inhibited (session lock)
and restore the cursor when the last grabbed output is removed.

- grab_interface becomes a member of wf_kill_view with a .cancel handler.
  output_t::set_inhibited(true) (session lock) calls cancel_active_plugins();
  previously wf-kill had no cancel callback, so its grab and activation
  survived the lock and the first left click after unlock closed (and with
  -k SIGKILLed) the window under the pointer.
- New wf_kill_view::cancel_grab(): release all grabs, drop the pending
  pirate-cursor idle call, restore the default cursor, send cancel to the
  requester. Used by the cancel handler and by the output pre-remove path,
  which previously did not restore the cursor.

diff --git a/src/plugin/wayfire-kill-view.cpp b/src/plugin/wayfire-kill-view.cpp
index 3c657b7..64fb13b 100644
--- a/src/plugin/wayfire-kill-view.cpp
+++ b/src/plugin/wayfire-kill-view.cpp
@@ -38,11 +38,6 @@
 #include "wayfire-kill-view.hpp"
 #include "wayfire-kill-view-server-protocol.h"
 
-wf::plugin_activation_data_t grab_interface{
-    .name = "wf-kill",
-    .capabilities = wf::CAPABILITY_GRAB_INPUT,
-};
-
 static void bind_manager(wl_client *client, void *data,
     uint32_t version, uint32_t id);
 
@@ -101,6 +96,24 @@ void wf_kill_view::release_grabs()
     grab_active = false;
 }
 
+/* Abort a live selection without closing anything (lock, output loss). */
+void wf_kill_view::cancel_grab()
+{
+    if (!grab_active)
+    {
+        return;
+    }
+
+    release_grabs();
+    idle_set_cursor.disconnect();
+    wf::get_core().set_cursor("default");
+    if (requester)
+    {
+        send_cancel(requester);
+        requester = nullptr;
+    }
+}
+
 void wf_kill_view::start_grab(wl_resource *resource)
 {
     /* One selection at a time; replacing a live grab orphans its scene node. */
@@ -196,6 +209,13 @@ void wf_kill_view::set_base_ptr(wf::pointer_interaction_t *base)
 
 wf_kill_view::wf_kill_view()
 {
+    /* Output inhibition (session lock) cancels active plugins; without this
+     * the selection would survive the lock and fire on the next click. */
+    grab_interface.cancel = [=] ()
+    {
+        cancel_grab();
+    };
+
     manager = wl_global_create(wf::get_core().display,
         &wf_kill_view_base_interface, 1, this, bind_manager);
 
@@ -216,15 +236,9 @@ wf_kill_view::wf_kill_view()
         it->second->ungrab_input();
         ev->output->deactivate_plugin(&grab_interface);
         input_grabs.erase(it);
-        if (input_grabs.empty() && grab_active)
+        if (input_grabs.empty())
         {
-            grab_active = false;
-            idle_set_cursor.disconnect();
-            if (requester)
-            {
-                send_cancel(requester);
-                requester = nullptr;
-            }
+            cancel_grab();
         }
     };
     wf::get_core().output_layout->connect(&on_output_pre_remove);
diff --git a/src/plugin/wayfire-kill-view.hpp b/src/plugin/wayfire-kill-view.hpp
index b7e5696..8e8210c 100644
--- a/src/plugin/wayfire-kill-view.hpp
+++ b/src/plugin/wayfire-kill-view.hpp
@@ -27,12 +27,17 @@
 #include <wayfire/plugins/common/input-grab.hpp>
 #include <wayfire/output-layout.hpp>
 #include <wayfire/view.hpp>
+#include <wayfire/plugin.hpp>
 
 class wf_kill_view
 {
     wl_global *manager;
 
   public:
+    wf::plugin_activation_data_t grab_interface{
+        .name = "wf-kill",
+        .capabilities = wf::CAPABILITY_GRAB_INPUT,
+    };
     wf::pointer_interaction_t *base;
     void set_base_ptr(wf::pointer_interaction_t *base);
     std::vector<wl_resource*> client_resources;
@@ -41,6 +46,7 @@ class wf_kill_view
     bool grab_active = false;
     void start_grab(wl_resource *resource);
     void release_grabs();
+    void cancel_grab();
     void client_destroyed(wl_resource *resource);
     void close_view(wayfire_view view, wl_resource *resource);
     void send_view_info(wl_resource *resource);