EXP-1790 FIX -- Hitting return on item in Merchant Outbox wears the object

* Disabled the "openItem" function on outbox items to prevent default behavior
  when the return button is pressed.

indra/newview/llpanelmarketplaceoutboxinventory.cpp

@@ -148,4 +148,9 @@ BOOL LLOutboxFolderViewItem::handleDoubleClick(S32 x, S32 y, MASK mask)
 	return TRUE;
 }
 
+void LLOutboxFolderViewItem::openItem()
+{
+	// Intentionally do nothing to block attaching items from the outbox
+}
+
 // eof

indra/newview/llpanelmarketplaceoutboxinventory.h

@@ -71,6 +71,7 @@ class LLOutboxFolderViewItem : public LLFolderViewItem
 
 	// virtual
 	BOOL handleDoubleClick(S32 x, S32 y, MASK mask);
+	void openItem();
 };