Fix a bunch of warnings

Mostly adding __unused where needed.

Change-Id: Ia4f675b9b360782728c361ed1699db0cc277c3a5
diff --git a/gui/listbox.cpp b/gui/listbox.cpp
index be2b486..0a53a7c 100644
--- a/gui/listbox.cpp
+++ b/gui/listbox.cpp
@@ -158,7 +158,7 @@
 
 	if (mVisibleItemsOld != mVisibleItems) {
 		mUpdate = 1; // some item's visibility has changed
-		if (firstDisplayedItem >= mVisibleItems.size()) {
+		if (firstDisplayedItem >= (int)mVisibleItems.size()) {
 			// all items in the view area were removed - make last item visible
 			SetVisibleListLocation(mVisibleItems.empty() ? 0 : mVisibleItems.size()-1);
 		}