seat: Drop has_exclusive_layer

[Nefsen402]

Fixes: #7936

In the transition to wlr_scene, I accidentally dropped a call to reset this has_exclusive_layer so once it was set, nothing could reset it afterwards and the compositor basically unusable. Let's just drop the has_exclusive_layer bool for something simpler and more robust.

[emersion]

Seems like we're loosing this condition here?

IOW, exclusive keyboard layers under the toplevels would never get focus before, but now they do.

[Nefsen402]

Why do we have this condition in the first place?

[emersion]

That's a decision we made when implementing layer-shell support. The motivation is that if a particular layer has focus, a lower level layer cannot get focus. So if a toplevel has focus, background/bottom cannot get focus.

[WhyNotHugo]

I used shotman to test this and sway crashes when shotman runs:

...
00:00:23.802 [wlr] [render/gles2/renderer.c:158] Created GL FBO for buffer 1280x720
00:00:23.802 [wlr] [render/swapchain.c:106] Allocating new swapchain buffer
00:00:23.802 [wlr] [render/allocator/gbm.c:144] Allocated 10x16 GBM buffer with format AR24 (0x34325241), modifier Y_TILED_GEN12_RC_CCS_CC (0x0100000000000008)
00:00:23.802 [wlr] [render/gles2/renderer.c:158] Created GL FBO for buffer 10x16
00:00:23.803 [wlr] [types/output/render.c:146] Disabling direct scan-out on output 'WL-1' (locks: 1)
00:00:23.803 [wlr] [types/output/cursor.c:44] Disabling hardware cursors on output 'WL-1' (locks: 1)
00:00:23.806 [sway/desktop/transaction.c:872] Transaction 0x7f6ba1c86620 is ready
00:00:23.806 [sway/desktop/transaction.c:682] Applying transaction 0x7f6ba1c86620
00:00:23.807 [sway/desktop/transaction.c:786] Transaction 0x7f6ba1c857f0 committing with 2 instructions
00:00:23.807 [sway/desktop/transaction.c:682] Applying transaction 0x7f6ba1c857f0
00:00:23.807 [wlr] [types/output/cursor.c:386] Falling back to software cursor on output 'WL-1'
00:00:23.814 [wlr] [types/output/render.c:146] Enabling direct scan-out on output 'WL-1' (locks: 0)
00:00:23.814 [wlr] [types/output/cursor.c:44] Enabling hardware cursors on output 'WL-1' (locks: 0)
Assertion failed: layer->surface->mapped (sway/input/seat.c: seat_set_focus_layer: 1328)
 err: wayland.c:1447: failed to read events from the Wayland socket: Connection reset by peer
 err: wayland.c:2019: failed to roundtrip Wayland display: Connection reset by peer
 err: wayland.c:2019: failed to roundtrip Wayland display: Connection reset by peer
 err: wayland.c:2019: failed to roundtrip Wayland display: Connection reset by peer
zsh: abort      ./build/sway/sway --config ./test.conf -d
 err: wayland.c:1984: failed to flush wayland socket: Connection reset by peer                                                                     

Output of WAYLAND_DEBUG=1 shotman --capture output: https://paste.sr.ht/blob/22620559ee800e1996579f5d7206a4c5c7bad980

Note that I tested a merge of this into master: Merge: dcdb7275 972fcc60.