File mate-calc-gtk-3.20.patch of Package mate-calc

--- a/configure.ac
+++ b/configure.ac
@@ -19,9 +19,9 @@ dnl ####################################
 dnl Dependencies
 dnl ###########################################################################
 
-GLIB_REQUIRED=2.50.0
+GLIB_REQUIRED=2.48.0
 GIO_REQUIRED=2.36.0
-GTK_REQUIRED=3.22.0
+GTK_REQUIRED=3.20.0
 
 PKG_CHECK_MODULES(MATE_CALC, [
     gtk+-3.0 >= $GTK_REQUIRED
--- a/src/math-window.c
+++ b/src/math-window.c
@@ -199,11 +199,18 @@ static void redo_cb(GtkWidget *widget, M
 static void help_cb(GtkWidget *widget, MathWindow *window)
 {
     GError *error = NULL;
+#if GTK_CHECK_VERSION(3, 22, 0)
 
     gtk_show_uri_on_window(GTK_WINDOW(window),
                            "help:mate-calc",
                            gtk_get_current_event_time(),
                            &error);
+#else
+    gtk_show_uri(gtk_window_get_screen(GTK_WINDOW(window)),
+                 "help:mate-calc",
+                 gtk_get_current_event_time(),
+                 &error);
+#endif
 
     if (error != NULL)
     {