boxPointer: Add compatibility API

Because we're late in the cycle, and don't know how many
extensions actually rely on this API, this commit adds
back the BoxPointer.show() and .hide() functions, with
warning messages to notify consumers that this is going
to be removed.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/153

js/ui/boxpointer.js

@@ -80,6 +80,36 @@ var BoxPointer = new Lang.Class({
         }
     },
 
+    // BoxPointer.show() and BoxPointer.hide() are here for only compatibility
+    // purposes, and will be removed in 3.32.
+    show(animate, onComplete) {
+        if (animate !== undefined) {
+            try {
+                throw new Error('BoxPointer.show() has been moved to BoxPointer.open(), this code will break in the future.');
+            } catch(e) {
+                logError(e);
+                this.open(animate, onComplete);
+                return;
+            }
+        }
+
+        this.visible = true;
+    },
+
+    hide(animate, onComplete) {
+        if (animate !== undefined) {
+            try {
+                throw new Error('BoxPointer.hide() has been moved to BoxPointer.close(), this code will break in the future.');
+            } catch(e) {
+                logError(e);
+                this.close(animate, onComplete);
+                return;
+            }
+        }
+
+        this.visible = false;
+    },
+
     open(animate, onComplete) {
         let themeNode = this.actor.get_theme_node();
         let rise = themeNode.get_length('-arrow-rise');