input/tablet: add seatop_down entry for tablet input

Currently, when tablet input exits a window during an implicit grab, it
passes focus to another window.

For instance, this is problematic when trying to drag a scrollbar, and
exiting the window — the scrollbar motion stops. Additionally,
without `focus_follows_mouse no`, the tablet passes focus to whatever
surface it goes over regardless of if there is an active implicit.

If the tablet is over a surface that does not bind tablet handlers, sway
will fall back to pointer emulation, and all of this works fine. It
probably should have consistent behavior between emulated and
not-emulated input, though.

This commit adds a condition for entering seatop_down when a tablet's
tool tip goes down, and exiting when it goes up. Since events won't be
routed through seatop_default, this prevents windows losing focus during
implicit grabs.

Closes #5302.

1 files changed, 8 insertions, 0 deletions

diff --git a/sway/input/seat.c b/sway/input/seat.c
index 233267e0..e5f15613 100644
--- a/sway/input/seat.c
+++ b/sway/input/seat.c
@@ -1471,6 +1471,14 @@ void seatop_pointer_axis(struct sway_seat *seat,
         }
 }
 
+void seatop_tablet_tool_tip(struct sway_seat *seat,
+                struct sway_tablet_tool *tool, uint32_t time_msec,
+                enum wlr_tablet_tool_tip_state state) {
+        if (seat->seatop_impl->tablet_tool_tip) {
+                seat->seatop_impl->tablet_tool_tip(seat, tool, time_msec, state);
+        }
+}
+
 void seatop_tablet_tool_motion(struct sway_seat *seat,
                 struct sway_tablet_tool *tool, uint32_t time_msec, double dx, double dy) {
         if (seat->seatop_impl->tablet_tool_motion) {