Basic example

jsPanel.create({
    content:     '<textarea name="editor1" id="editor1"></textarea>',
    contentSize: '750 400',
    headerTitle: 'jsPanel with CKEditor',
    theme:       'primary',
    position:    'center-top 0 70',
    callback: function () {
        CKEDITOR.replace('editor1', {
            height: 295
        });
        $('#btn-1').attr('disabled', 'disabled');
    },
    resizeit: {
        resize: function (panel) {
            resizeEditor(panel);
        }
    },
    onmaximized: function (panel) {
        resizeEditor(panel);
    },
    onnormalized: function (panel) {
        resizeEditor(panel);
    },
    onclosed: function () {
        $('#btn-1').attr('disabled', false);
    }
});

// function to resize the editor area whenever panel is resized using mouse or maximize/normalize methods
function resizeEditor(panel) {
    var h = parseInt(panel.content.style.height) - 105;
    $('.cke_contents', panel.content).css('height', h);
}