Rewrite _preferredIconSize method for icon sizing

[joevnpro]

Refactor _preferredIconSize method to prioritize manual input and UI slider for icon size calculation.

Refactor _preferredIconSize method for clarity and wider limitation (smaller to bigger)

[icedman]

Thanks for this. This solves icon scaling issues. Could you think of a why to adjust the settings of users. So as not to surprise them with the sudden icon size change.

[joevnpro]

I noticed a faulty initialization and a lack of a strong two-way link between the icon resizing slider on the UI control. This needs fixing.

Then, setting the initial/default position for the slider should work (the current initial position should always be the smallest). Or, use the slider position value that the user has already set.

Alternatively: provide a "what's new" notification to let them know and allow them to make changes.

Alternatively: make changes gradually. Increase or decrease the min/max values ​​gradually over several updates, each time by no more than 15%, to allow users to adapt.