[Wayland] Candidate list for Fcitx5 immediately disappears/flickers in fullscreen windows (text-input-v3)

[layercak3]

SDL main 6187edd (issue also present in 2.0.22)
Latest sway from master branch + swaywm/sway#5890
Latest wlroots from master branch

I am using Fcitx5 for non-Latin alphabet input with the candidate list. On non-SDL windows like foot, GTK, etc. the candidate list shows up fine, even in fullscreen. On SDL however it works in windowed mode but if I put it in fullscreen the candidate list doesn't appear. I can still type text and press enter, and pretext works, just not the candidate list popup. Please let me know if it is reproducible or not in case it is not an SDL issue.

Used SuperTuxKart and osu!lazer

[flibitijibibo]

Here's where SDL implements the protocol for input rectangle: https://github.com/libsdl-org/SDL/blob/main/src/video/wayland/SDL_waylandkeyboard.c#L55

This has been checked under other compositors and with ibus, not sure about fcitx. Quick search suggested native Wayland might have been an issue at one point:

fcitx/fcitx5#206 (comment)

(The author actually submitted some patches for both X and Wayland support recently, so I'd expect this to work!)

[diagonalisability]

I can't reproduce this issue, Fcitx5's candidate list doesn't flicker for me on a fullscreen SDL window. Maybe this was fixed, or maybe this was a Sway bug?

• Sway version 1.7
• SDL version 2.24 (also tried most recent commit, 6af1736)

I tried building that Sway PR, but it doesn't build with the latest version of Wlroots.

[diagonalisability]

I was able to build that Sway PR by rebasing it onto Sway master, but I still can't reproduce this bug.

• Sway commit I rebased onto: 9400bd9
• Latest Wlroots commit: 0c962c9
• Programs I've tested: Osu Lazer, this minimal SDL program

[layercak3]

I'm in sway 9400bd963c59fd59f597c1477b8021a82ca0a72e, wlroots eeb7a8113869790e5f6fc643bafa577b08b5f4c3, fcitx5 da7c3ceda592558728108603c1d936f4230c8f96, sdl2 2.24.1

I've used swaywm/sway#5890, swaywm/sway#7226, and https://aur.archlinux.org/cgit/aur.git/tree/0001-text_input-Implement-input-method-popups.patch?h=sway-im-git implementations and got the same issue in supertuxkart and osu lazer (IME popup not visible unless not in fullscreen, can sometimes see it flicker very slightly in osu when typing. Happens in mozc, and table methods like IPA-X-SAMPA). I could try reproducing in a vm, testing default config and screen record the issue in the coming days if I have some time

[diagonalisability]

I'm also not getting any flickering in Supertuxkart, the candidate list displays fine. I've tried using Fcitx5 with Mozc, and I've tried both Sway 1.7 and Sway master + swaywm/sway#5890. Does this bug happen for you when you use Sway 1.7 without any additional commits?

[layercak3]

Sorry for the long delay. I am using SDL 9e8d2f3 and rebased swaywm/sway#7226 on sway swaywm/sway@5543acf (commit of 1.7 release), and got the same behaviour as before. Note I have always used the HEAD of wlroots master, not a release ver

[layercak3]

I found a clue. When I set my output (display) to a scale that is fractional, I can see it (tested 0.5, 1.1, 0.9, 2.9, even stuff like 0.999999 works where it looks almost identical to 1). But when I am using an integer scale (tested 1, 2, 3) I don't see it. (also I switched back to sway HEAD)