Size text fields according to the likely size of the content they will contain. This gives a useful visual cue to the amount of input expected and prevents overflow.

In an instant-apply dialog, validate the contents of the entry field when it loses focus or when the window is closed, not after each keypress. Exception: if the field accepts only a fixed number of characters, such as a hexadecimal color code, validate and apply the change as soon as that number of characters have been entered.

If you implement an entry field that only accepts certain characters, such as digits, play the system warning beep when the user tries to type an invalid character.

Normally, pressing Tab in a single-line entry field should move focus to the next control, and in a multi-line entry field it should insert a tab character. Pressing CtrlTab in a multi-line entry field should move focus to the next control.

If you need to provide a keyboard shortcut that inserts a tab character into a single line entry field, use CtrlTab. You are unlikely to find many situations where this is useful, however.

An icon at the beginning of the entry can be used to indicate its purpose - replacing the need for the entry to be labelled. Search entry fields are the classic example of this, where a search icon is placed on the left side of the entry field.

If the text to be entered is case sensitive, a warning icon can be shown inside the text field if caps lock is on. This is typically shown on the right side of the entry.

If it is common for the text field to be cleared, a clear icon button can be placed inside the field, at the right side.

If you place an icon in a text entry field (either as an indicator or a button), use its symbolic variant from the GNOME Symbolic Icon Theme.

GtkEntry

GtkSearchEntry