I have some settings that the user of my software can change via a GUI. The settings reflect both the current state of the underlying properties, and the state of the user interaction.
Example: A slider which initially gets its value from the underlying properties. When the user interacts with the slider, the value of the slider changes, but it doesn't propagate to the underlying layer, until the user clicks a button.
Now, the user needs to know when there is an unsaved change to the slider, and so far I have colored the slider red, and it gets colored black when the user clicks the save button.
However, this choice of alerting the user, is completely arbitrary, and I was wondering if there is a more generally accepted way of notifying the user of changes like these?