jqmdialogfix.css

.ui-dialog-background {
    opacity: 0.5;
    display: block !important;
}

.ui-dialog-background.pop.in {
    opacity: 1;
}

.ui-dialog {
    min-height: 100% !important;
    background: transparent !important;
}

jqmdialogfix.js

$(function() {
    $(document).on("pageinit", function (e) {
        $(document).on('pagebeforeshow', '[data-role="dialog"]', function (e, ui) {
            if (ui.prevPage.data('role') != 'dialog') {
                ui.prevPage.addClass("ui-dialog-background");
            }
        });

        $(document).on('pagehide', '[data-role="dialog"]', function (e, ui) {
            if (ui.nextPage.data('role') != 'dialog') {
                $(".ui-dialog-background ").removeClass("ui-dialog-background");
            }
        });
    });
});