[DC 6.2.3] Opening a file dialog in multimedia/video/mediaplayer example shows cursor only in directory selection line

Tested with Device Creation version 6.2.3 (sha: e9282c060:987aca0e4)

Steps to reproduce:

1. Install any device creation toolchain and qt creator (imx8qm-mek used in testing)
2. Open Qt Creator and Examples/multimedia/video/mediaplayer
3. Apply https://codereview.qt-project.org/c/qt/qtmultimedia/+/390368/2/examples/multimedia/video/mediaplayer/CMakeLists.txt
4. Build and run the example application
5. From example select File -> Open
6. Move cursor around

Expected result:

Cursor is shown all the time when moving

Actual result:

Cursor is shown only when it is over the file dialog's directory selection line