QWidget rarely receives unintentional mouse press/release events with tslib

We usually enables tslib with QT_QPA_EGLFS_TSLIB or QT_QPA_FB_TSLIB environment variable on embedded linux.

https://doc.qt.io/qt-5/inputs-linux-device.html#touch

Then a mousehandler for tslib is created.

https://code.qt.io/cgit/qt/qtbase.git/tree/src/plugins/platforms/linuxfb/qlinuxfbintegration.cpp?h=5.15.2#n161

When  QT_QPA_GENERIC_PLUGINS=tslib is also set, Qt will creates another mousehandler for tslib.

https://code.qt.io/cgit/qt/qtbase.git/tree/src/plugins/generic/tslib/main.cpp?h=5.15.2#n59

Because of the duplication, QWidget rarely receives additional mouse press/release events against single touch operation.

To avoid the issue, do not set QT_QPA_GENERIC_PLUGINS=tslib when you want to use tslib.