The current implementation of the ImageResourceGenerator works very well for most of the browsers. However in IE6 you have the problem that it will convert everything to the PNG format (also if it was a GIF before). In IE6 you will need to add a filter to display transparent PNGs correctly. Theses filters consume a lot (too much) memory. If you have a couple of them on your page, your page will be unusable very fast. The ImageBundle support in older GWT versions also has this problem. However this should be fixed.
There is a solution for this: ImageResourceGenerator should not change the format to PNG if we have a GIF. IE6 can display transparent GIFs very well. The problem is that GWT handles IE6 and IE7 the same. IE7 can handle transparent PNGs. So for the best output for this solution we would need to add another deferred binding for IE7. The ResourceContext interface would get another method supportsTransparentPNG (like supportsDataUrls). IE7 could use the MhtmlResourceContentext and return true for that method. IE6 would return false (we would have two MhtmlResourceContentext which are almost the same). The ImageResourceGenerator would than decide how to handle the image (like it already checks now for support of data urls). I really think this should be handled within GWT. For the current GWT releases we have overrides in place to fix the memory usage at least in IE7 as we can use PNGs there without filters. The normal implementation of GWT sets up filters also in IE7. I could do the changes and would contribute them back to you. What do you think? Sven Brunken Ext GWT Core Developer --~--~---------~--~----~------------~-------~--~----~ http://groups.google.com/group/Google-Web-Toolkit-Contributors -~----------~----~----~----~------~----~------~--~---
