The DrRacket window contains a number of different pieces of status information that tries to expose what DrRacket is doing in a relatively unobtrusive way.
The name of the language that DrRacket is currently using. This is also a popup menu that you can use to change the language from a list of recently used languages.
Further over to the right are some numbers showing the line and column or the character offset of the insertion point (where characters will appear when you next type).
The current heap size that DrRacket is using internally. The number is updated infrequently; to see the accurate number, click on it, which also triggers a major garbage collection.
An small square that is blank unless DrRacket is doing a garbage collection and a recycle icon when DrRacket is doing garbage collection.
A narrow blank space or a pair of parentheses. If DrRacket is working to determine the colors and where the matching parentheses are in the definitions, that will be a pair of parentheses and if not, it will be blank.
A small person that indicates if DrRacket is running the program in the interactions window or not. (The person will run when DrRacket is running your program.)
A circle that indicates the status of DrRacket’s online expansion (only available when using “Determine language from source”). If it is red, there is an error in the program or the online expansion has been disabled. If it is blue, DrRacket is working to expand your program. If it is (dark or light) purple, DrRacket is processing the result of the expansion to compute where the arrows go and which how renaming any given variable affects any of the others. If it is green, DrRacket’s online expansion has finished. If it is a spiky green ball (instead of a round green ball), then DrRacket will use the result of the online expansion to speed up the Run button. That is, when the green spiky ball is present, DrRacket will not expand or compile your program, but just run it directly.