Odd Flex Builder Errors

I have been developing a flex MXML control for an AIR application that lets me easily change the font, font size, list box horizontal and vertical spacing, etc. I just hooked up a font picker list that shows a sample of each font, and I made the size of the font list dynamically controlled by the slider for font size. This all happens in a popup window, so as the font settings dialog list of font names is dynamically reacting to the user moving the sliders, the application window beneath is also reacting and redrawing itself in real time. Very cool.

I wewnt to look at the design view for my control, and I got this error:

Tags defining the value of the default property "mxmlContentFactory" must be adjacent with no other tags between them

Now to start the process of gradually backing out changes to my control to try and figure out what is causing this...

The problem was this:

The extra Script tag in between the HGroups of the BorderContainer confused Flex Builder. Everything would compile fine, and there were no warnings flagged in the left margin.

I had put the extra script block to put the variable near the controls it was being used in. Moving that declaration up to the main script block, and then deleting this script block, fixed the problem.