A puzzle icon in the visualization mod title indicates that you are able to develop the mod, and you click it to access the development popup. If the puzzle icon is not visible, development is turned off.
You can switch between these two states by selecting Tools > Development > Enable development for mods in analysis or Tools > Development > Disable development for mods in analysis.
Development is enabled automatically when you start the development of a new visualization mod. If you exit Spotfire, development of the mod is disabled by default. Next time the analysis is opened, the user will not see any puzzle icon.