GUI BUG: file picker on Linux KDE Plasma does not handle mouse, unusable

[ValdikSS]

VirtualBox file picker dialog (ISO or HDD selection, etc) does not handle mouse events when running on KDE Plasma 5. All dialog elements are not clickable. You can still use it with keyboard.

When opening the dialog, Qt outputs the following warning into console:

Qt WARNING: QWidgetWindow(0x681e4a0, name="UIMachineSettingsStorageWindow") must be a top level window.

I'm not sure whether is this a Qt, VirtualBox, KDE Plasma or packaging issue, but Mageia bug reporter ​https://bugs.mageia.org/show_bug.cgi?id=27433 says that rebuilding the same package under older version of distro fixes the issue.

This is happening in Virtualbox 6.1.18 too, but only in Plasma5. Doesn't happen under GNOME. Curiously the same .src.rpm rebuilt under Mageia7 doesn't show up the problem under Plasma.

Also reproducible on Fedora 33 with RPMFusion repository. Bug: ​https://bugzilla.rpmfusion.org/show_bug.cgi?id=5929#c1

### HOW TO REPRODUCE

1. Open VirtualBox
2. Create new VM or use existing
3. Open VM settings
4. Go to "storage" tab
5. Click on any drive → cilck on HDD or optical icon → Choose a disk file… dropdown element

### EXPECTED RESULT File picker dialog works as usual, you can select ISO or disk drive file with a mouse.

### ACTUAL RESULT You can't click on any dialog element.

### WORKAROUND Quick and dirty patch is in the attachment.

KDE Plasma: 5.20.5 KDE Frameworks: 5.78.0 Qt version: 5.15.2

[ValdikSS]

VBox File picker patch

[gombara]

I cannot reproduce this. Tried on a development build from the top of our 6.1 branch on a KDE Plasma 5 (Linux Mint 20.1).

[Omano]

I can confirm this exact same issue on Manjaro KDE. It has been like that for months now.

[ValdikSS]

Replying to gombara:

I cannot reproduce this. Tried on a development build from the top of our 6.1 branch on a KDE Plasma 5 (Linux Mint 20.1).

This might be Qt related. Could you please test with Fedora 33?

[ValdikSS]

Workaround:

KDE_FULL_SESSION= XDG_CURRENT_DESKTOP= DESKTOP_SESSION= virtualbox

[ValdikSS]

Here's a proper patch: ​https://build.opensuse.org/package/view_file/Virtualization/virtualbox/vb-6.1.16-modal-dialog-parent.patch?expand=1

[Rob Gillen]

FYI, I was able to reproduce this issue in with VirtualBox 6.1.32 r149290 on Kubuntu 21.10 (impish), which uses KDE Frameworks 5.86.0 (Plasma 5.22.5). The workaround seems to be working on my machine.

[gombara]

This bug has been fixed for VirtualBox version > 6.1.34.