This allows some relevant events, in particular ClientMessage with WM_TAKE_FOCUS and PropertyNotify for WM_STATUS updates to go through even when QS_POSTMESSAGE is not set. Before this change, if an application was not processing posted messages, it would fail to obtain focus, and also leave WM status updates pending.
Previously, use_take_focus was disabled on Proton by default because x11drv would fail to respond to TAKE_FOCUS events properly. We are now looking to drop this hack in favor of processing the relevant events.