LXQt panel: grouped window popup disappears on mouseover with patched versions of Qt5 (in Arch)

[DanielPrjct]

Description:

Arch Linux (up-to-date) with LXQt.

I've updated my system at 2021/04/08 and 2021/04/09 and since qt5-... packages versions are qt5-....version+kde+version, LXQt panel doesn't allow to select and maximize/resize any grouped minimized window.
As example: two or more Qterminal instances in the same desktop, or Thunderbird main window and its Write window in other desktop.

Grouped windows are showed (pop up menu appears with left click) by LXQt Panel, but when I try to select one minimized window, the pop up menu dissapear.

Once all windows in the same desktop are minimized and showed in LXQt Panel, neither of them can be maximized nor resized from LXQt taskbar (Task Manager).

The only updated packages that I can see perhaps related to this bug are:
qt5-base 5.15.2+kde+r171-2
qt5-declarative 5.15.2+kde+r24-1
qt5-svg 5.15.2+kde+r5-1
qt5-wayland 5.15.2+kde+r11-1 ? (I'm not using Wayland at all).
All are now "mainversion+kde+version"...

Downgrading to previous "non-kde" versions seems solve the issue...

Additional info:

• package version(s)

liblxqt 0.16.0-1
lximage-qt 0.16.0-1 (lxqt)
lxqt-about 0.16.0-1 (lxqt)
lxqt-admin 0.16.0-1 (lxqt)
lxqt-archiver 0.3.0-1 (lxqt)
lxqt-config 0.16.1-1 (lxqt)
lxqt-globalkeys 0.16.0-1 (lxqt)
lxqt-notificationd 0.16.0-1 (lxqt)
lxqt-openssh-askpass 0.16.0-1 (lxqt)
lxqt-panel 0.16.1-1 (lxqt)
lxqt-policykit 0.16.0-1 (lxqt)
lxqt-powermanagement 0.16.0-1 (lxqt)
lxqt-qtplugin 0.16.0-1 (lxqt)
lxqt-runner 0.16.0-1 (lxqt)
lxqt-session 0.16.0-1 (lxqt)
lxqt-sudo 0.16.0-1 (lxqt)
lxqt-themes 0.16.0-1 (lxqt)
obconf-qt 0.16.0-1 (lxqt)
openbox 3.6.1-7 (lxde lxde-gtk3 lxqt)
pcmanfm-qt 0.16.0-1 (lxqt)
qterminal 0.16.1-1 (lxqt)
qt5-base (5.15.2-5 -> 5.15.2+kde+r171-1)
qt5-svg (5.15.2-2 -> 5.15.2+kde+r5-1)
qt5-declarative (5.15.2-1 -> 5.15.2+kde+r24-1)
qt5-wayland (5.15.2-1 -> 5.15.2+kde+r11-1)

Expected Behavior

Open two or more instances of an application in different windows at the same desktop, or open a dialog window of an application, and then minimize one or more windows. They will be grouped at task manager. Left click in each group must show its minimized windows and allow select what window must be maximized or resized.

Current Behavior

Left click in a group in Task Manager pop up a lit of minimized windows, but they dissapear immediatly, or when user try to select one of them hovering the cursor.

Possible Solution

@arojas, KDE and qt5 maintainer at Arch Linux team, says that this issue is caused by this Qt change;
[url]
https://code.qt.io/cgit/qt/qtbase.git/commit/?h=5.15&id=62f86b9b7ab3421c7a74c4c05a186847c76bfb28
[/url]

Steps to Reproduce (for bugs)

Context

System Information

• Distribution & Version: Arch Linux
• Kernel: 5.11.12-arch1-1
• Qt Version: 5.15.2-5
• liblxqt Version: liblxqt 0.16.0-1
• Package version: qt5-base 5.15.2-5

[tsujan]

What your described under "Current Behavior" isn't reproducible.

If you think you could describe the problem in a better way, explain it in a step by step way under "Steps to Reproduce" (1..., 2.....)

[tsujan]

Downgrading to previous "non-kde" versions seems solve the issue...

If so, you already know that the problem isn't in LXQt; why opening an issue here?

[DanielPrjct]

@tsujan:
I have not enough knowledge to analyze if the bug is LXQt related, QT5 related or Arch Linux packaging related.
@arojas, KDE and qt5 maintainer at Arch Linux team, asked me to report the problem to the upstream LXQt developer team.
So I have reported the issue here... I'm sorry if this report causes "noises"...
I don't know how to proceed, now :-(

[DanielPrjct]

Steps to Reproduce (for bugs)
An example:

1. Open Thunderbird main window.
2. Create a new message (Write)
3. Minimize Write (new message) window, it appears in Task Manager of LXQt Panel, under Thunderbird group.
4. Try to resize or maximize Write minimized window, selecting it by hovering the cursor on Thunderbird group.
5. Minimized window is showed for a brief moment, but user is unable to select or click on it.
6. This issue only appears using the last updated qt5 libraries: qt5-base 5.15.2+kde+r171-1, qt5-svg 5.15.2+kde+r5-1, qt5-declarative 5.15.2+kde+r24-1, qt5-wayland 5.15.2+kde+r11-1...

[tsujan]

@DanielPrjct
This page will be re-opened if any LXQt member encounters the problem you mentioned. Closing an issue doesn't mean forgetting it.

As for reporting an issue, please include the relevant info and avoid long comments. As far as I was able to extract it from your comments, what you told was as simple as this:

After upgrading Qt to the versions "5.15.2+kde..." provided by Arch, the popup of grouped windows in Panel's task manager disappears as soon as you move the mouse cursor over it.

This can be a distro issue, a problem in Arch packages "5.15.2+kde...", or a new bug in Qt. In the last case, a backward compatible workaround might be needed.

Thanks for the report!

[stefonarch]

Reproducible here, at 5. no way to select any window in the group because list disappears.
I upgraded arch yesterday.
Also right click → close group is broken and probably middle click closing too (don't remember if it was allowed first).

Steps to Reproduce (for bugs)
An example:

1. Open Thunderbird main window.
2. Create a new message (Write)
3. Minimize Write (new message) window, it appears in Task Manager of LXQt Panel, under Thunderbird group.
4. Try to resize or maximize Write minimized window, selecting it by hovering the cursor on Thunderbird group.
5. Minimized window is showed for a brief moment, but user is unable to select or click on it.
6. This issue only appears using the last updated qt5 libraries: qt5-base 5.15.2+kde+r171-1, qt5-svg 5.15.2+kde+r5-1, qt5-declarative 5.15.2+kde+r24-1, qt5-wayland 5.15.2+kde+r11-1...

[tsujan]

@stefonarch
Thanks! I'll get that version when it comes to Manjaro Testing; it shouldn't take long. If that happens in 2-3 days and a backward-compatible workaround is found, we might want to add it to 0.17.0; otherwise, a point release might be needed.

[antonio-rojas]

this is not "a patched version of Qt5". As mentioned above, this is caused by an actual upstream Qt commit, https://code.qt.io/cgit/qt/qtbase.git/commit/?h=5.15&id=62f86b9b7ab3421c7a74c4c05a186847c76bfb28

[tsujan]

It's patched by using upstream patches (and "...+kde+r..." shows that). The official releases are here: https://download.qt.io/official_releases/qt/5.15/

[tsujan]

@stefonarch
Could you test if the following change makes a difference?

diff -ruNp lxqt-panel-orig/plugin-taskbar/lxqttaskgroup.cpp lxqt-panel/plugin-taskbar/lxqttaskgroup.cpp
--- lxqt-panel-orig/plugin-taskbar/lxqttaskgroup.cpp
+++ lxqt-panel/plugin-taskbar/lxqttaskgroup.cpp
@@ -576,7 +576,8 @@ void LXQtTaskGroup::dragLeaveEvent(QDrag
 void LXQtTaskGroup::mouseMoveEvent(QMouseEvent* event)
 {
     // if dragging the taskgroup, do not show the popup
-    setPopupVisible(false, true);
+    if (event->buttons() & Qt::LeftButton)
+        setPopupVisible(false, true);
     LXQtTaskButton::mouseMoveEvent(event);
 }
 

[antonio-rojas]

Tha patch fixes the problem for me.

[tsujan]

@antonio-rojas
Thanks a lot! Two questions:

1. If you start to drag the task button of grouped windows while the popup is shown, the popup should disappear. Does that happen?
2. On right clicking the task button of grouped windows, another popup appears; it says, "Close group". Does it work with the above change?

[antonio-rojas]

@antonio-rojas
Thanks a lot! Two questions:

1. If you start to drag the task button of grouped windows while the popup is shown, the popup should disappear. Does that happen?
2. On right clicking the task button of grouped windows, another popup appears; it says, "Close group". Does it work with the above change?

Yes to both.

[tsujan]

Yes to both.

Good :) I'll make a PR today.

[stefonarch]

Tested the PR, looks fine.