Here are a few useful controls written in Flex 4 for displaying prompt text, and for showing an icon in a button.
The IconButton class extends the defaults Flex 4 Button class, and adds the icon style as well as the labelPlacement (left, right, top, bottom) and paddingLeft, paddingTop, paddingRight, and paddingBottom styles.
I also made a simple extension of the TextInput class which shows a prompt text when the text input is empty and not in focus, it is called PromptingTextInput.
The third example is called ClearTextInput, it extends PromptingTextInput to show a small clear button (which is a IconButton) on the right hand side of the text input whenever there is text inside the text input.
The fourth example is what I call a PromptingList. It shows a prompt text whenever the list is empty. This is useful if you have a list that gets populated from a remote service (e.g "Loading..."), or if your list gets items added to it by the user, or by dragging items into the list (as in the example below).
Each of the prompting controls supports a style called promptStyleName which lets you set the styleName for the prompt Label.
** Note that the package structure has been renamed to flex.utils.spark.* for all Spark controls.
Here it is: