diff -urN Pale-Moon-27.4.0_Release/browser/app/profile/palemoon.js Pale-Moon-27.4.0_Release-patched/browser/app/profile/palemoon.js
--- Pale-Moon-27.4.0_Release/browser/app/profile/palemoon.js	2017-07-10 22:23:16.000000000 +1000
+++ Pale-Moon-27.4.0_Release-patched/browser/app/profile/palemoon.js	2017-07-13 00:17:14.911617742 +1000
@@ -232,7 +232,7 @@
 pref("general.useragent.complexOverride.moodle", false); // bug 797703
 
 // At startup, check if we're the default browser and prompt user if not.
-pref("browser.shell.checkDefaultBrowser", true);
+pref("browser.shell.checkDefaultBrowser", false);
 pref("browser.shell.shortcutFavicons",true);
 
 // 0 = blank, 1 = home (browser.startup.homepage), 2 = last visited page, 3 = resume previous browser session