Restore previous mouse position when leaving the editor freelook mode

- Remove the crosshair as it no longer serves a purpose (the cursor will
  now appear where the user "expects" it to).

This closes https://github.com/godotengine/godot-proposals/issues/1076.

(cherry picked from commit 4a542e0007b6288ca328eafe5819e58b92bbad15)

editor/icons/icon_crosshair.svg

@@ -1 +0,0 @@
-<svg height="16" viewBox="0 0 16 16" width="16" xmlns="http://www.w3.org/2000/svg"><path d="m6 1v5h-5v1 3h5v5h4v-5h5v-4h-5v-5z" fill-opacity=".627451"/><path d="m2 7v2l5.0000803.0000197-.0000803 4.9999803h2l-.0000803-4.9999803 5.0000803-.0000197v-2l-5.0000803.0001803.0000803-5.0001803h-2l.0000803 5.0001803z" fill="#fefefe" fill-opacity=".862745"/></svg>

editor/plugins/spatial_editor_plugin.cpp

@@ -2189,6 +2189,8 @@ void SpatialEditorViewport::set_freelook_active(bool active_now) {
 			freelook_speed = base_speed * cursor.distance;
 		}
 
+		previous_mouse_position = get_local_mouse_position();
+
 		// Hide mouse like in an FPS (warping doesn't work)
 		Input::get_singleton()->set_mouse_mode(Input::MOUSE_MODE_CAPTURED);
 
@@ -2198,6 +2200,11 @@ void SpatialEditorViewport::set_freelook_active(bool active_now) {
 
 		// Restore mouse
 		Input::get_singleton()->set_mouse_mode(Input::MOUSE_MODE_VISIBLE);
+
+		// Restore the previous mouse position when leaving freelook mode.
+		// This is done because leaving `Input.MOUSE_MODE_CAPTURED` will center the cursor
+		// due to OS limitations.
+		warp_mouse(previous_mouse_position);
 	}
 
 	freelook_active = active_now;
@@ -2359,13 +2366,6 @@ void SpatialEditorViewport::_notification(int p_what) {
 		call_deferred("update_transform_gizmo_view");
 	}
 
-	if (p_what == NOTIFICATION_READY) {
-		// The crosshair icon doesn't depend on the editor theme.
-		crosshair->set_texture(get_icon("Crosshair", "EditorIcons"));
-		// Set the anchors and margins after changing the icon to ensure it's centered correctly.
-		crosshair->set_anchors_and_margins_preset(PRESET_CENTER);
-	}
-
 	if (p_what == NOTIFICATION_PROCESS) {
 
 		real_t delta = get_process_delta_time();
@@ -2489,10 +2489,6 @@ void SpatialEditorViewport::_notification(int p_what) {
 			current_camera = camera;
 		}
 
-		// Display the crosshair only while freelooking. Hide it otherwise,
-		// as the crosshair can be distracting.
-		crosshair->set_visible(freelook_active);
-
 		if (show_info) {
 			String text;
 			text += "X: " + rtos(current_camera->get_translation().x).pad_decimals(1) + "\n";
@@ -3846,10 +3842,6 @@ SpatialEditorViewport::SpatialEditorViewport(SpatialEditor *p_spatial_editor, Ed
 	camera->make_current();
 	surface->set_focus_mode(FOCUS_ALL);
 
-	crosshair = memnew(TextureRect);
-	crosshair->set_mouse_filter(MOUSE_FILTER_IGNORE);
-	surface->add_child(crosshair);
-
 	VBoxContainer *vbox = memnew(VBoxContainer);
 	surface->add_child(vbox);
 	vbox->set_position(Point2(10, 10) * EDSCALE);

editor/plugins/spatial_editor_plugin.h

@@ -266,8 +266,8 @@ private:
 
 	bool freelook_active;
 	real_t freelook_speed;
+	Vector2 previous_mouse_position;
 
-	TextureRect *crosshair;
 	Label *info_label;
 	Label *cinema_label;
 	Label *locked_label;