prefs.js: don't show 'Adaptive' option for Gnome < 3.26.

prefs.js

@@ -7,6 +7,7 @@ const Gtk = imports.gi.Gtk;
 const Gdk = imports.gi.Gdk;
 const Lang = imports.lang;
 const Mainloop = imports.mainloop;
+const Config = imports.misc.config;
 
 // Use __ () and N__() for the extension gettext domain, and reuse
 // the shell domain with the default _() and N_()
@@ -73,6 +74,42 @@ function setShortcut(settings) {
     }
 }
 
+/** Compare two dotted version strings (like '10.2.3').
+ * @returns {Integer} 0: v1 == v2, -1: v1 < v2, 1: v1 > v2
+ * Copied from https://github.com/paradoxxxzero/gnome-shell-system-monitor-applet/, compat.js.
+ */
+function versionCompare(v1, v2) {
+    let v1parts = ('' + v1).split('.')
+    let v2parts = ('' + v2).split('.')
+    let minLength = Math.min(v1parts.length, v2parts.length)
+    let p1, p2;
+    // Compare tuple pair-by-pair.
+    for (let i = 0; i < minLength; i++) {
+        // Convert to integer if possible, because "8" > "10".
+        p1 = parseInt(v1parts[i], 10);
+        p2 = parseInt(v2parts[i], 10);
+
+        if (isNaN(p1))
+            p1 = v1parts[i];
+        if (isNaN(p2))
+            p2 = v2parts[i];
+
+        if (p1 === p2)
+            continue;
+        else if (p1 > p2)
+            return 1;
+        else if (p1 < p2)
+            return -1;
+
+        // one operand is NaN
+        return NaN;
+    }
+    // The longer tuple is always considered 'greater'
+    if (v1parts.length === v2parts.length)
+        return 0;
+    return (v1parts.length < v2parts.length) ? -1 : 1;
+}
+
 const Settings = new Lang.Class({
     Name: 'DashToDock.Settings',
 
@@ -628,6 +665,10 @@ const Settings = new Lang.Class({
             }
         }));
 
+        // We need to hide the 'Adaptive' option for < Gnome 3.26
+        if (versionCompare(Config.PACKAGE_VERSION, '3.26') === -1)
+            this._builder.get_object('customize_opacity_combo').remove(2);
+
         // Create dialog for transparency advanced settings
         this._builder.get_object('dynamic_opacity_button').connect('clicked', Lang.bind(this, function() {