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26.7% Duplication

Maybe to avoid duplication it would be worth it to abstract the this.showFilterMenu function callback to its own function, e.g. like this:

function showFilterMenuCb(query, mode, filterchangeCb) {
    import('../../components/filterdialog/filterdialog').then(({ default: filterDialogFactory }) => {
        const filterDialog = new filterDialogFactory({
            query,
            mode,
            serverId: ApiClient.serverId()
        });
        Events.on(filterDialog, 'filterchange', filterchangeCb);
        filterDialog.show();
    });
}

And then e.g. in movies.js we could replace the current this.showFilterMenu implementation with this:

    this.showFilterMenu = showFilterMenuCb.bind(this, query, 'movies', () => {
        query.StartIndex = 0;
        userSettings.saveQuerySettings(savedQueryKey, query);
        itemsContainer.refreshItems();
    });

I have a concern with this... our current UI does not have any indication when a filter is active. I can see this causing an influx of issues where people have forgotten they set a filter and are confused why some of their content is not being displayed.

Understandable, I guess I could look into implementing such indicator if desired.

This pull request has merge conflicts. Please resolve the conflicts so the PR can be successfully reviewed and merged.

This was implemented in #5717