patch 8.2.4619: mapping is cancelled when mouse moves and popup is visible

Problem:    Mapping is cancelled when mouse moves and popup is visible.
Solution:   Only generate mouse moved events when a popup may use them.
            (closes #10004)
diff --git a/src/gui.c b/src/gui.c
index fb589fc..3e383a4 100644
--- a/src/gui.c
+++ b/src/gui.c
@@ -4968,7 +4968,7 @@
     gui_mouse_focus(x, y);
 
 #ifdef FEAT_PROP_POPUP
-    if (popup_visible)
+    if (popup_uses_mouse_move)
 	// Generate a mouse-moved event, so that the popup can perhaps be
 	// closed, just like in the terminal.
 	gui_send_mouse_event(MOUSE_MOVE, x, y, FALSE, 0);