Qt6 version of Bitcoin Core (bitcoin-qt) flickers on Wayland

[diegoviola]

Issues, reports or feature requests related to the GUI should be opened directly on the GUI repo

• I still think this issue should be opened here

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So I've just tried the v30.0 release and I have it up and running on Arch Linux, bitcoin-qt is running natively on Wayland (sway).

After using the GUI for a while, I have noticed that the whole window would flicker, e.g. when switching between "Overview" and "Transactions".

This never happened before, and I think the reason for that is because the app would use Xwayland prior to Qt 6.

So yes, one way of avoiding this problem is to start bitcoin-qt with QT_QPA_PLATFORM=xcb, however, I would very much like this to work with the Wayland native plugin, which is used by default.

I did some small experimentation and have found that when commenting the following line, the problem is gone:

https://github.com/bitcoin/bitcoin/blob/v30.0/src/qt/guiutil.cpp#L411

Thanks!

[hebasto]

After using the GUI for a while, I have noticed that the whole window would flicker, e.g. when switching between "Overview" and "Transactions".

Does it look similar to bitcoin/bitcoin#33432?

[diegoviola]

Does it look similar to bitcoin/bitcoin#33432?

Yes, it does look like the same issue.

[hebasto]

So I've just tried the v30.0 release and I have it up and running on Arch Linux, bitcoin-qt is running natively on Wayland (sway).

Could you please share the first 10 lines of your debug log file?

[diegoviola]

So I've just tried the v30.0 release and I have it up and running on Arch Linux, bitcoin-qt is running natively on Wayland (sway).

Could you please share the first 10 lines of your debug log file?

2025-10-14T14:47:07Z Bitcoin Core version v30.0 (release build)
2025-10-14T14:47:07Z Qt 6.10.0 (dynamic), plugin=wayland
2025-10-14T14:47:07Z No static plugins.
2025-10-14T14:47:07Z Style: fusion / QFusionStyle
2025-10-14T14:47:07Z System: Arch Linux, x86_64-little_endian-lp64
2025-10-14T14:47:07Z Screen: HDMI-A-1 1920x1200, pixel ratio=1.0
2025-10-14T14:47:07Z Using the 'x86_shani(1way;2way)' SHA256 implementation
2025-10-14T14:47:07Z Using RdSeed as an additional entropy source
2025-10-14T14:47:07Z Using RdRand as an additional entropy source
2025-10-14T14:47:07Z Default data directory /home/diego/.bitcoin

[hebasto]

2025-10-14T14:47:07Z Qt 6.10.0 (dynamic), plugin=wayland
2025-10-14T14:47:07Z No static plugins.

Could you please try the release binary from https://bitcoincore.org/bin/bitcoin-core-30.0/ or build a statically linked binary with depends?

EDIT: Both options have only the XCB plugin built in and do not use Wayland. I just want to ensure that release binaries are not affected on your system.

[diegoviola]

2025-10-14T14:47:07Z Qt 6.10.0 (dynamic), plugin=wayland
2025-10-14T14:47:07Z No static plugins.

Could you please try the release binary from https://bitcoincore.org/bin/bitcoin-core-30.0/ or build a statically linked binary with depends?

EDIT: Both options have only the XCB plugin built in and do not use Wayland. I just want to ensure that release binaries are not affected on your system.

Sure, I just tried the latest release (v30.0) from bitcoincore.org, here is the log:

2025-10-14T16:28:38Z Bitcoin Core version v30.0.0 (release build)
2025-10-14T16:28:38Z Qt 6.7.3 (static), plugin=xcb
2025-10-14T16:28:38Z Static plugins:
2025-10-14T16:28:38Z  QMinimalIntegrationPlugin, version 395008
2025-10-14T16:28:38Z  QXcbIntegrationPlugin, version 395008
2025-10-14T16:28:38Z Style: fusion / QFusionStyle
2025-10-14T16:28:38Z System: Arch Linux, x86_64-little_endian-lp64
2025-10-14T16:28:38Z Screen: HDMI-A-1 1920x1200, pixel ratio=1.0
2025-10-14T16:28:38Z Using the 'x86_shani(1way;2way)' SHA256 implementation
2025-10-14T16:28:38Z Using RdSeed as an additional entropy source
2025-10-14T16:28:38Z Using RdRand as an additional entropy source
2025-10-14T16:28:38Z Default data directory /home/diego/.bitcoin

No issues with this release build, presumably because it's using plugin=xcb.

[diegoviola]

@hebasto @pablomartin4btc can we just get rid of the problematic code in this case? According to this comment: swaywm/sway#4739 (comment)

"Qt.WindowStaysOnTopHint won't work on Wayland. Clients don't get to dictate whether they stay on top or not.".

[pablomartin4btc]

can we just get rid of the problematic code in this case?

I'll take a look...

[diegoviola]

I'll take a look...

Appreciate you planning to look into that, I managed to track down the cause and submitted a fix in #904. Let me know if you have any questions during the review. Thanks!