focus-stack: Keep dragged surface in focus stack in move_request()

Replacement for https://github.com/pop-os/cosmic-comp/pull/1687, that
works correctly with multiple outputs.

We don't want another window to show a focus indicator while a window is
being dragged, so keep the window in the focus stack. If a window is
being moved out of a stack, change the focus from the stack to the
window.

`refresh_focus_stack()` doesn't seem to be called here, but for good
measure, make sure that calling that function also won't remove a
`CosmicMapped` from the focus stack if it is currently part of a move
grab for the seat.

src/shell/focus/mod.rs

@@ -129,11 +129,11 @@ impl FocusStackMut<'_> {
         self.0.insert(target);
     }
 
-    pub fn remove<T>(&mut self, target: &T)
+    pub fn remove<T>(&mut self, target: &T) -> bool
     where
         T: Hash + indexmap::Equivalent<FocusTarget>,
     {
-        self.0.shift_remove(target);
+        self.0.shift_remove(target)
     }
 
     pub fn last(&self) -> Option<&FocusTarget> {

src/shell/mod.rs

@@ -3415,15 +3415,6 @@ impl Shell {
             return None;
         }
 
-        if !move_out_of_stack {
-            for workspace in self.workspaces.spaces_mut() {
-                for seat in self.seats.iter() {
-                    let mut stack = workspace.focus_stack.get_mut(seat);
-                    stack.remove(&old_mapped);
-                }
-            }
-        }
-
         let (window, _) = old_mapped
             .windows()
             .find(|(w, _)| w.wl_surface().as_deref() == Some(surface))
@@ -3441,6 +3432,15 @@ impl Shell {
             old_mapped.clone()
         };
 
+        if move_out_of_stack {
+            // Update focus stack to set focus to the window being dragged out of
+            // the stack.
+            if let Some(workspace) = self.space_for_mut(&old_mapped) {
+                let mut stack = workspace.focus_stack.get_mut(seat);
+                stack.append(mapped.clone());
+            }
+        }
+
         let trigger = match &start_data {
             GrabStartData::Pointer(start_data) => Trigger::Pointer(start_data.button),
             GrabStartData::Touch(start_data) => Trigger::Touch(start_data.slot),

src/shell/workspace.rs

@@ -7,7 +7,7 @@ use crate::{
         element::{AsGlowRenderer, FromGlesError},
     },
     shell::{
-        ANIMATION_DURATION, OverviewMode,
+        ANIMATION_DURATION, OverviewMode, SeatMoveGrabState,
         layout::{floating::FloatingLayout, tiling::TilingLayout},
     },
     state::State,
@@ -455,17 +455,33 @@ impl Workspace {
     }
 
     pub fn refresh_focus_stack(&mut self) {
-        for stack in self.focus_stack.0.values_mut() {
+        for (seat, stack) in self.focus_stack.0.iter_mut() {
             let fullscreen = self
                 .fullscreen
                 .as_ref()
                 .filter(|f| f.alive())
                 .filter(|f| f.ended_at.is_none())
                 .map(|f| &f.surface);
+
+            // Move grab is treated as focused, so don't change focus to a
+            // window while grab exists.
+            let move_grab_state = seat
+                .user_data()
+                .get::<SeatMoveGrabState>()
+                .unwrap()
+                .lock()
+                .unwrap();
+            let move_mapped = if let Some(move_grab_state) = &*move_grab_state {
+                Some(move_grab_state.element())
+            } else {
+                None
+            };
+
             let mapped = || {
                 self.floating_layer
                     .mapped()
                     .chain(self.tiling_layer.mapped().map(|(w, _)| w))
+                    .chain(move_mapped.iter())
             };
             stack.retain(|w| match w {
                 FocusTarget::Fullscreen(s) => fullscreen.is_some_and(|f| f == s),