Fixes Shortcuts prevent inputs with AltGr #29021

[YoannQDQ]

Fixes #29021

Description

A long standing bug in QGIS is the inability to enter some characters (}, |, ...) on windows, with keyboard layouts that use the AltGr key (Spanish, French...). This is particularly annoying within the python console.

The reason is that Qt considers by default the AltGr key to be a shortcut for Ctrl+Alt, which causes some QGIS global shortcuts to be fired instead of entering the character.

There has been some discussion about this on PR #38608.
This is not specific to QGIS, as it happens in other Qt applications (see https://bugreports.qt.io/browse/QTBUG-73247)

Setting the environment variable QT_QPA_PLATFORM=windows:altgr before creating the QgsApplication on windows builds could neatly solve the issue. (cf. https://doc.qt.io/qt-6/qguiapplication.html#platform-specific-arguments)

[YoannQDQ]

I'm not sure this is the right way to do it, but it seems to work (at least for the portable version on Windows)

[DelazJ]

@YoannQDQ Can you add a more verbose and explicit title to the pull request, please? Thanks

[nyalldawson]

Looks good to me, I'd love a second opinion though!

[YoannQDQ]

Huh. Pipeline failed, but if I understand the logs correctly, it's not on me. Could someone trigger another run?

[roya0045]

Strange, I never had any issues with key modifiers.

[YoannQDQ]

Strange, I never had any issues with key modifiers.

Which OS/keyboard layout do you use?
On Windows 10, AZERTY french layout, I just can't enter } or | unless I disable some shortcuts.

[roya0045]

Strange, I never had any issues with key modifiers.

Which OS/keyboard layout do you use? On Windows 10, AZERTY french layout, I just can't enter } or | unless I disable some shortcuts.

Qwerty with can-fr or can-multilingual layout. Win10

[agiudiceandrea]

@roya0045, the issue also occurs using the Italian and Spanish keyboard layouts (as reported in the issue report).
On Windows, with every keyboard that maps to a char any AltGr key combination also mapped by default in QGIS as an Ctrl+Alt key combination, it is impossible to type such char in the Python console.
For the Italian and Spanish keyboard layouts the issue is with the ] char (AltGr++ / Ctrl+Alt++ Zoom In).

[uclaros]

Just curious, is Q_OS_WIN referring to the host at compile time or the build target?