ActiveX_Child_Tabbing

Created Date: 9/7/2007
Last Updated: 5/21/2008
Description: A UI Toolkit program, an ActiveX control, and some other associated files that demonstrate how you can control tabbing when a composite window includes an ActiveX control that has multiple controls (two edit controls in this case) and that uses TAB and SHIFT+TAB internally.
Platforms: Windows
Products: UI Toolkit; ActiveX API
Minimum Version: 9.1
Author: Chip Camden

Additional Information: Testtab.dbl is a UI Toolkit program that controls the way tabbing works with an ActiveX Control that

-- uses TAB and SHIFT+TAB internally (i.e., it processes these as accelerators), which prevents users from tabbing out of the child.

-- includes two edit controls.

For the first issue, the control is coded to invoke a method that signals the "C_NEXT" or "C_PREV" menu entry at the point a user would tab out of the control. (Note this isn't necessary for many ActiveX controls. If a control uses TAB and SHIFT+TAB internally but returns them as unprocessed when it reaches the end of its own tabbing order, TAB and SHIFT+TAB do tab out of the child. This is usually how controls created with VB6 work.)

For the second issue, if an ActiveX control consists of more than one control and has its own tabbing order, focus within the ActiveX control may not be where you want it when the user tabs to the ActiveX control. For this program, the ActiveX control consists of two edit controls, and focus within the ActiveX control generally lands on the edit control that last had focus. To work around this, the Toolkit program includes a composite window processing method that in turn uses a method in the ActiveX control to set focus.

The important parts of the Synergy code are the two functions at the end of testtab.dbl:

-- The mfcctl_process function (used as the child window method when C_PROCESS processes the ActiveX window) instructs the control to focus the correct edit control depending on the reason for achieving focus. It also instructs the runtime (via ax_wantskey) that the control wants to process TAB and SHIFT+TAB.

-- The mfcctl_tabout function is an event handler for the control's Tabout event. This is fired by the control whenever a TAB or SHIFT+TAB results in tabbing off either end of the control's own internal tabbing order.

The ActiveX control is written in C++, and the sources are included so you can see how the control fires the required Tabout event.