In Qt6, check boxes emit integers instead of the proper enum (https://bugreports.qt.io/browse/QTBUG-104688). Current logic for enabling/disabling layer artists checks the value emitted against the Qt.CheckState enum, which means that the user cannot make a layer artist they have turned not-visible visible again.
This PR fixes this behavior in the layer artist view by checking for the type of the value emitted by the checkbox and adds a test for it. I have not exhaustively checked that this problem does not occur with other checkboxes elsewhere in the GUI with Qt 6.
Description
In Qt6, check boxes emit integers instead of the proper enum (https://bugreports.qt.io/browse/QTBUG-104688). Current logic for enabling/disabling layer artists checks the value emitted against the Qt.CheckState enum, which means that the user cannot make a layer artist they have turned not-visible visible again.
This PR fixes this behavior in the layer artist view by checking for the type of the value emitted by the checkbox and adds a test for it. I have not exhaustively checked that this problem does not occur with other checkboxes elsewhere in the GUI with Qt 6.