I am new to this forum though I have been building with the Flash Builder Beta Release for a long time now.
I have somewhat of a complex scenario and I'll try to explain things as succinctly and simply as possible.
I have a "main container" that is built in Flex 3 and it loads Flex 4 applications into it via SWFLoader attached to an MDI instance (using the MDI library from the flexlib library).
Adobe's contention is that this configuration is unsupported, and I understand this. It is my intention to port the Flex 3 container to Flex 4 however that is a challenge as I am using a number of compiled libraries in this container that simply don't work in Flex 4. Also, in order to do this, I have to target Flash Player 10 when compiling the Flex 3 container.
The Flex 4 apps I am loading into the Flex 3 container have a lot of features from Flex 4 I want to use which is why I am using Flex 4 in the first place.
With the Beta 1 release, everything works as expected.
With the Beta 2 release, two major problems emerge.
I'll explain the first one as it is a bit harder to explain.
Picture an MDI window instance with a Flex 4 content added to it attached to a Flex 3 container. Now picture there are items to the right and underneath that MDI instance in the Flex 3 container. With the Beta 2 release, those items to the right and underneath the Flex 4 content fail to receive any mouse interactivity whatsoever - no click, double click, mouseover, etc. events. It is like the Flex 4 content continues invisibly beyond the upper right and lower left boundaries. This does NOT occur in the Beta 1 release.
Next major problem. Now imagine there are two of these MDI Window instances with Flex 4 content loaded into them. The Flex 4 content implements an AdvancedDataGrid implementation and the Flex 4 content is set up in such a way that they are in sibling ApplicationDomains in the same SecurityDomain as the main container. In the Beta Release 1, this enables content to be dragged and dropped from the ADG in MDI Window 1 to the ADG in MDI Window 2. In the Beta Release 2, as soon as the dragged item leaves the boundaries of the MDI Window where it is being dragged from, a compiler error is thrown reporting DragEvent errors. It appears as if the DragManager is not recognizing the DragEvent that the Flex 4 content is dispatching.
So I thought to myself, well I really can't submit this as a bug. Because my configuration is unsupported by Adobe - i.e. loading Flex 4 content into a Flex 3 container.
So I decided it was finally time to move in the direction of porting my Flex 3 container to Flex 4 - even though I won't be able to use a lot of the features I'd like to because I have no way to port some libraries to Flex 4.
After spending all day porting the other day, sure enough, the problems I report above continue. They have nothing to do with loading Flex 4 content into a Flex 3 container.
This completely disrupts my workflow and has me continuing my main container in Flex 3, and further, rolling back to the Beta 1 release of Flash Builder for my Flex 4 apps I'll be loading into the Flex 3 container.
I hope someone can provide some insight into the problems I am reporting or perhaps facilitate some recommendations.