Gregory
Wow
Deep stuff...
I'll dive right in

A million thanks!
Jaime

>>Hi All
>>I am building an interfacing solution between my VFP app and a third-party app. The users Alt-Tab to the external app, do some stuff, then Alt-Tab back to the VFP app. At that specific moment i would like to run some code. What events are trigered when the VFP app gets the focus back using Alt-Tab?
>>
>>TIA
>>Jaime
>
>Jaime,
>
>There are imo three solutions
>
>(1) Work with a timer. Each timer event captures the foreground window. If it has changed and has become the vfp window, then you can fire the code
>

>declare integer GetForegroundWindow in Win32API
>

>
>(2) The simplest. If you want the event to occur when a specific form is run by the user, let the form
>

>ShowWindow = 2 && as top level form
>

>As far as I can see, the form activate() fires
>
>(3) use api SetWinEventHook().
>You will need the callback from the download section
>I've made a sample on how to proceed below (minimal testing, I confess, there may be an error left, but it is a start)
>While making the sample, I've learnt that you can capture almost anything
>Best thing to do would be to wrap this in a class
>
>Fires when _screen activates, ie even when focus goes from a ShowWindow = 2 to the main vfp window
>
>Good luck
>
>

>#define GWL_HINSTANCE	(-6)
>
>#define EVENT_MIN           0x00000001
>#define EVENT_MAX           0x7FFFFFFF
>
>#define EVENT_SYSTEM_SOUND              0x0001
>#define EVENT_SYSTEM_ALERT              0x0002
>#define EVENT_SYSTEM_FOREGROUND         0x0003
>#define EVENT_SYSTEM_MENUSTART          0x0004
>#define EVENT_SYSTEM_MENUEND            0x0005
>#define EVENT_SYSTEM_MENUPOPUPSTART     0x0006
>#define EVENT_SYSTEM_MENUPOPUPEND       0x0007
>#define EVENT_SYSTEM_CAPTURESTART       0x0008
>#define EVENT_SYSTEM_CAPTUREEND         0x0009
>#define EVENT_SYSTEM_MOVESIZESTART      0x000A
>#define EVENT_SYSTEM_MOVESIZEEND        0x000B
>#define EVENT_SYSTEM_CONTEXTHELPSTART   0x000C
>#define EVENT_SYSTEM_CONTEXTHELPEND     0x000D
>#define EVENT_SYSTEM_DRAGDROPSTART      0x000E
>#define EVENT_SYSTEM_DRAGDROPEND        0x000F
>#define EVENT_SYSTEM_DIALOGSTART        0x0010
>#define EVENT_SYSTEM_DIALOGEND          0x0011
>#define EVENT_SYSTEM_SCROLLINGSTART     0x0012
>#define EVENT_SYSTEM_SCROLLINGEND       0x0013
>#define EVENT_SYSTEM_SWITCHSTART        0x0014
>#define EVENT_SYSTEM_SWITCHEND          0x0015
>#define EVENT_SYSTEM_MINIMIZESTART      0x0016
>#define EVENT_SYSTEM_MINIMIZEEND        0x0017
>
>#define WINEVENT_OUTOFCONTEXT   0x0000  && Events are ASYNC
>#define WINEVENT_SKIPOWNTHREAD  0x0001  && Don't call back for events on installer's thread
>#define WINEVENT_SKIPOWNPROCESS 0x0002  && Don't call back for events on installer's process
>#define WINEVENT_INCONTEXT      0x0004  && Events
>
>function do_it()
>	
>	set library to \projectnet\vfp\release\vfp.fll additive && adjust path
>
>	declare long SetWinEventHook in win32api ;
>		integer eventMin, ;
>		integer eventMax, ;
>		long hmodWinEventProc, ;
>		long lpfnWinEventProc, ;
>		long idProcess, ;
>		long idThread, ;
>		long dwflags ;
>	
>	declare integer UnhookWinEvent in win32api ;
>		long hWinEventHook
>
>	declare long GetWindowLong in win32api long hwnd, long nIndex
>	declare long FindWindow in win32api   string @lpClassName,  string @WindowName
>	declare long GetCurrentThreadId in win32api
>	declare long GetWindowThreadProcessId in win32api ;
>		integer	hWnd, long @pid
>	
>	if( type('_screen.hwnd') == T_UNDEFINED ) && I'm still on vfp6
>		_screen.AddProperty('hwnd', FindWindow(null, _screen.Caption))
>	endif
>	
>	public HookFunction, hHook
>	HookFunction = CallBack_Set( 'HookCalled', 'iiiiiii')
>	local hMod, ProcessId
>	hMod = GetWindowLong(FindWindow(null, _screen.Caption), GWL_HINSTANCE)
>	
>	ProcessId = 1
>	ThreadId = GetWindowThreadProcessId(_screen.hwnd, @ProcessId)
>	
>	hHook = SetWinEventHook( EVENT_SYSTEM_FOREGROUND, EVENT_SYSTEM_FOREGROUND, hMod, HookFunction, ProcessId, GetCurrentThreadId(), WINEVENT_INCONTEXT)
>	
>	&& this needs to be done at some point in time
>	&& in this order
>	&& before vfp exits or library unloaded, or it crashes on quit
>	suspend
>	?UnhookWinEvent(hHook)
>	?CallBack_Release(HookFunction)
>endfunc
>*---------------------------------------------------------------------------
>function HookCalled(hWinEventHook, iEvent, hwnd, idObject, idChild, dwEventThread, dwmsEventTime)
>	
>  && any error in this function, like referencing a variable that does not exist, will crash vfp
>
>	*?hHook, _screen.hwnd
>	*?hWinEventHook, iEvent, hwnd, idObject, idChild, dwEventThread, dwmsEventTime
>	
>    && The tests below are not really necessary since
>    &&   (1) event min and max are set to EVENT_SYSTEM_FOREGROUND
>    &&   (2) we only track this process
>    &&
>	do case
>	case iEvent == EVENT_SYSTEM_FOREGROUND
>		do case
>		case hwnd == _screen.hwnd
>			acti screen
>			? 'vfp on  foreground'
>		endcase
>	endcase
>	
>	return 0
>endfunc
>*---------------------------------------------------------------------------
>