This patch removes InlineMessage's DropShadow for the following reasons:
1. consistency - there are no shadows in QWidgets' inline messages
2. visual hierarchy - shadows add depth, making the message seem like it
is floating over the window's conten and thereby also making the message
2. visual hierarchy - shadows add depth, making the message seem like it is floating over the window's content and thereby also making the message seem fairly prominent
3. aesthethics - no shadows means a cleaner look