diff -uNrBbwp palemoon-31.0.0/palemoon/platform/modules/libpref/init/all.js palemoon-31.0.0-new/palemoon/platform/modules/libpref/init/all.js

--- palemoon-31.0.0/palemoon/platform/modules/libpref/init/all.js	2022-05-14 17:13:00.000000000 +0000

+++ palemoon-31.0.0-new/palemoon/platform/modules/libpref/init/all.js	2022-05-15 03:10:19.746388115 +0000

@@ -3860,7 +3860,7 @@ pref("autocomplete.ungrab_during_mode_sw

 // Default to using the system filepicker if possible, but allow

 // toggling to use the XUL filepicker

-pref("ui.allow_platform_file_picker", true);

+pref("ui.allow_platform_file_picker", false);

 // Allow for using the native GTK file picker. If the application is not run

 // with GTK_USE_PORTAL=1 this pref has no effect.

diff -uNrBbwp palemoon-31.0.0/palemoon/platform/widget/gtk/nsWidgetFactory.cpp palemoon-31.0.0-new/palemoon/platform/widget/gtk/nsWidgetFactory.cpp

--- palemoon-31.0.0/palemoon/platform/widget/gtk/nsWidgetFactory.cpp	2022-05-14 17:13:00.000000000 +0000

+++ palemoon-31.0.0-new/palemoon/platform/widget/gtk/nsWidgetFactory.cpp	2022-05-15 03:11:28.867882674 +0000

@@ -144,7 +144,7 @@ nsFilePickerConstructor(nsISupports *aOu

   }

   bool allowPlatformPicker =

-      Preferences::GetBool("ui.allow_platform_file_picker", true);

+      Preferences::GetBool("ui.allow_platform_file_picker", false);

   nsCOMPtr<nsIFilePicker> picker;

   if (allowPlatformPicker) {