Edit Control Differences

In a version 3.x application, an edit control that is the descendant of an inactive window takes the input focus when the user clicks the control; an edit control in a version 4.0 application does not. Not taking the input focus prevents the situation where the user can enter text into what appears to be an inactive window.

An edit control in a version 3.x application retrieves its text and background colors by sending the WM_CTLCOLOREDIT message to its parent window. In a version 4.0 application, an edit control sends the WM_CTLCOLOREDIT or WM_CTLCOLORSTATIC message. The edit control sends WM_CTLCOLORSTATIC if it is disabled or read-only; otherwise, it sends WM_CTLCOLOREDIT. In addition, a disabled multiline edit control in a version 4.0 application uses the COLOR_GRAYTEXT value as its text color.

A multiline edit control in a version 4.0 application has a proportional scroll box (thumb), but a multiline edit control in a version 3.x application does not.

In a version 3.x application, the wParam parameter of the EM_REPLACESEL message is not used. In a version 4.0 application, the wParam parameter is a flag that specifies whether the replacement operation can be undone.