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Drop-down lists

A drop-down list is a user interface element which allows the user to select from a list of mutually exclusive options. It appears as a button which, when clicked, reveals a list.

Radio buttons or a list will often be preferable to a drop-down list, as they present all the available options at once without any further interaction. At the same time, a drop-down list might be a better choice when:

  • The number of options is large.

  • There is little available space.

  • The list of options may change over time.

  • The contents of the hidden part of the menu are obvious from its label and the one selected item. For example, if you have an option menu labelled “Month:” with the item “January” selected, the user might reasonably infer that the menu contains the 12 months of the year without having to look.

General guidelines

  • While GTK does provide a specific combobox widget, it is recommended that drop-down lists are constructed using a combination of a button and a popover. This allows more comfortable scrolling for long lists, and allows search to be integrated into the list. Using this approach also allows the current selected item to always be displayed.

  • If the number of items is very large, provide a search function that filters the list.

  • Label the drop-down list button with a text label above it or to its left, using sentence capitalization. Provide an access key in the label that allows the user to give focus directly to the drop-down list.

  • Use sentence capitalization for drop-down list items, for example Switched movement.

Custom values

A drop-down list can allow custom values to be added to a number of presets, or can be used to enter and select from custom values alone.

  • Ensure that custom values are ordered in a way that is most useful to users. Alphabetical or recency ordering is common.

  • When a drop-down list includes both preset and custom values, separate them into separate groups within the list.

  • Allow custom values to be removed from the list.

  • Validate custom values as they are entered, in order to prevent errors.

  • If the drop-down only accepts custom values, and no values have been entered previously, present the custom value entry when the drop-down is opened, instead of showing an empty list.