shell: Handle WorkspaceMode::Global in move_workspace()

If workspaces span across outputs, the `Workspace` at a particular
index should be moved on every `WorkspaceSet`.

src/shell/mod.rs

@@ -928,6 +928,8 @@ impl Workspaces {
             return;
         };
 
+        match self.mode {
+            WorkspaceMode::OutputBound => {
                 // Check which workspace is active on the new set; before removing from the
                 // old set in cause we're moving an active workspace within the same set.
                 let new_set = &mut self.sets[&new_output];
@@ -974,6 +976,46 @@ impl Workspaces {
 
                 new_set.update_workspace_idxs(workspace_state);
             }
+            WorkspaceMode::Global => {
+                let old_set = &mut self.sets[&old_output];
+                let old_idx = old_set
+                    .workspaces
+                    .iter()
+                    .position(|w| w.handle == *handle)
+                    .unwrap();
+
+                let new_set = &mut self.sets[&new_output];
+                let other_idx = new_set
+                    .workspaces
+                    .iter()
+                    .position(|w| w.handle == *other_handle)
+                    .unwrap();
+
+                // Move workspace at given index on every output
+                for set in self.sets.values_mut() {
+                    if old_idx < set.workspaces.len() && other_idx < set.workspaces.len() {
+                        let previous_active_handle = set.workspaces[set.active].handle;
+
+                        if other_idx > old_idx {
+                            let insert_idx = if after { other_idx } else { other_idx - 1 };
+                            set.workspaces[old_idx..=insert_idx].rotate_left(1);
+                        } else {
+                            let insert_idx = if after { other_idx + 1 } else { other_idx };
+                            set.workspaces[insert_idx..=old_idx].rotate_right(1);
+                        }
+
+                        set.active = set
+                            .workspaces
+                            .iter()
+                            .position(|w| w.handle == previous_active_handle)
+                            .unwrap();
+
+                        set.update_workspace_idxs(workspace_state);
+                    }
+                }
+            }
+        }
+    }
 
     pub fn update_config(
         &mut self,