Dynamic Data Exchange (DDE)

Dynamic data exchange is performed between windows. Thus, conversion of bidirectional text, if required, is based on the bidirectional attributes of the windows which are involved in the data exchange.

• The conversion is performed at WinDdePostMsg() time, using the hwndTo and hwndFrom bidi attributes (which are parameters of the WinDdePostMsg API).

• Bidi-aware applications can force no conversion by setting the bidi attributes of any window that is involved in the data exchange to 0.

• Conversion is done only for WM_DDE_DATA messages and only when the format of data being exchanged is DDEFMT_TEXT.

Notes:

• It is recommended that application names and item names (that are used by an application in the process of "making the DDE contact" with other applications) are in English. This is because conversions occur only at WM_DDE_DATA and not in WM_DDE_INITIATE time, and also because at WM_DDE_INITIATE time, there is no window handle from which the system can deduce the bidi attribute of the application name and item text.

• It is recommended that bidi-aware applications use "invisible" windows (or object windows) as the DDE source and target windows. This gives them the freedom to set their windows bidi attributes to any value without having to worry about the visual effect this may have on the display.