At the end of the day, Flex is Flash; an HTML or JSP page will have a swf file embedded in it and the Flash Player plug-in will be used to render it. Until now, most of our Flex and Flash projects have consisted of either small components within a page, or the entire page itself. In both cases the default “wmode” parameter value has always been used: “window.” Integrating the WYSIWYG control within our Flex component required using a different wmode value: opaque.
In order to integrate the WYSIWYG control into our Flex component we had to use iframes and this is what necessitated the use of the opaque wmode value. A quick Google search for “Flex iframes” turns up quite an interesting selection. One of the top hits is a project on Google Code called flex-iframe. We actually wound up using this component as it’s quite robust and works well. However, the first hit is an article titled “Don’t Use IFrames for HTML in Flex” and lists reasons why using iframes and Flex/Flash is a bad idea. One of the reasons is specifically because it requires the use of the opaque wmode value and lists the following three reasons:
- Speed: There is no big surprise here, but when you force Flash to composite the HTML layers above and below, you are adding additional processor load.
- Accessibility: wmode makes your movie invisible to screen readers
- Inconsistent Performance
So what did we end up doing? Several things:
- To address the performance issue we wound up not embedding FCK in our form multiple times. Instead we embedded a simple html page that we updated when the user changed content. The WYSIWYG only appears when the user clicks in the html area, via a modal popup.
- The scrolling issue fix was easy to implement, however, thinking of it took a bit of time. We initially tried some of the suggested fixes posted on the JIRA page, but they didn’t seem to work us. Since the issue only affected the UI while the user was scrolling the page, we decided to simply disable “live scrolling.” That is, the user can move the scrollbar normally but the rest of the UI won’t update until the user lets go of the scrollbar.