This was intentionally enabled with WindowModes as a new Taskbar
convenience, but on second thought, it doesn't add up visually.
Taskbar buttons show blockers' context menus when available,
which is a bit confusing when the window isn't visible. The
modeless window's disabled context menu options and inactive title
bar also contradict the button. So, this patch reenables the
restriction for now. Blocking modals you don't want to answer to
immediately can still be tucked away on another workspace.
This patch allows to insert "%uid" in `IPC_CLIENT_CONNECTION`
declaration and in SystemServer's ini files. This pattern is replaced
then replaced by the UID of the owner of the service. It opens a path
for seamlessly managed, per-user portal.
