KDE Visual Design Group/HIG/LineEdit
Edit controls display a single line of text to the user and allow the user to enter unconstrained text. A line edits is used to enter one line of text. If more than one line is required a text edit is the right control. Because edits are unconstrained and don’t accept valid data only, input validation and problem handling should be handled carefully.
- Use edits for input of unconstrained text. If only a specific type of data is valid, use other controls.
- Mask letters if edit is used to enter passwords.
- When setting a new password, have it entered twice to prevent typos in passwords.
- Provide a "Show password" check box to unmask the password both when setting new and when entering existing passwords.
- Consider to use auto-complete feature to help users when entering data that is likely to be used repeatedly.
- Don't make users scroll unnecessarily; size text boxes to eliminate the need for scrolling.
- Don't put horizontal scroll bars on multi-line text boxes.
- When disabling edit or text box, also disable any associated labels and buttons.
- If the user enters a character that is known to be invalid, ignore the character and display an input problem hint that explains the valid characters (e.g. numbers vs. characters).
- If the input data has a value or format that is known to be invalid, display an input problem hint when the text box loses input focus (e.g. wrong zip code format).
- If the input data is inconsistent with other controls on the window, give an error message when the entire input is complete, such as when users click OK for a modal dialog box.
- Don't clear invalid input data unless users aren't able to correct errors easily. Doing so allows users to correct mistakes without starting over.