Make filter show no flatpaks status page

If a filter is configured in such a way that no flatpaks will be shown, the no flatpaks status page is shown

src/window.py

@@ -480,6 +480,7 @@ def applyFilter(self, filter=[True, False, ["all"], ["all"]]):
         show_runtimes = filter[1]
         filter_install_type = filter[2]
         filter_remotes_list = filter[3]
+        total_visible = 0
 
         for i in range(len(self.flatpak_rows)):
             self.flatpak_rows[i][0] = True
@@ -498,6 +499,17 @@ def applyFilter(self, filter=[True, False, ["all"], ["all"]]):
 
             self.flatpak_rows[i][2].set_visible(self.flatpak_rows[i][0])
 
+            if self.flatpak_rows[i][0]:
+                total_visible += 1
+
+        if total_visible > 0:
+            #self.main_stack.set_visible_child(self.main_box)
+            self.windowSetEmpty(False)
+        else:
+            # self.main_stack.set_visible_child(self.no_flatpaks)
+            self.windowSetEmpty(True)
+            self.filter_button.set_sensitive(True)
+
     def __init__(self, **kwargs):
         super().__init__(**kwargs)
         self.my_utils = myUtils(self)