Here the way I found (without using the event handler) to show the tool tip over the image :
#include <GUIConstantsEx.au3>
#include <IE.au3>
#include <WindowsConstants.au3>
#include <GUIToolTip.au3>
$HTML = "http://www.hamqsl.com/solar101pic.php"
$SD = GUICreate("Solar data", 600, 180)
$futurebutton1 = GUICtrlCreateLabel("Visit N0NBH's site for more Banners..", 460, 50, 120, 100)
GUICtrlSetFont(-1, 14, 200, 0, "Arial")
Global $oIE = _IECreateEmbedded()
$hIE = GUICtrlCreateObj($oIE, 10, 10, 435, 160)
_IENavigate($oIE, 'about:blank', 1)
_IENavigate($oIE, $HTML, 1)
$oDocument = $oIE.document
$oDocument.body.scroll = "no"
GUISetState(@SW_SHOW)
Global $oEventObject = ObjEvent($oDocument, "IEEvent2_", "HTMLDocumentEvents2")
If @error Then Exit MsgBox($MB_OK, "AutoIt COM Test", "ObjEvent: Can't use event interface. Error code: " & Hex(@error,8))
Local $aPos, $aPosPrec = [0,0]
While 1
$aPos = GUIGetCursorInfo ($SD)
If Not @error Then
If $aPos[0] >= 15 And $aPos[0] <= 430 And $aPos[1] >= 15 And $aPos[1] <= 155 Then
If $aPos[0] <> $aPosPrec[0] Or $aPos[1] <> $aPosPrec[1] And WinActive ($SD) Then
ToolTip ("Click Image to add Solar-Terrestrial Data to your website!")
$aPosPrec[0] = $aPos[0]
$aPosPrec[1] = $aPos[1]
EndIf
Else
ToolTip ("")
EndIf
EndIf
Switch GUIGetMsg()
Case $GUI_Event_Close
ExitLoop
EndSwitch
WEnd
Volatile Func IEEvent2_onClick($oEvent)
If $oEvent.srcElement.NodeName = "IMG" Then
ToolTip ("")
ShellExecute("http://www.hamqsl.com/solar.html")
EndIf
EndFunc ;==>IEEvent2_onClick