tdf#96739: Send Ctrl-Left/RightShift events to correct window

Another regression from commit 74407aef. SystemWindow should
consume only Alt pressed/released events and let key input window
handle the rest of modkey events

Change-Id: I304701fe63ee86bad534ba003ea05991d06f433d
Reviewed-on: https://gerrit.libreoffice.org/21854Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Katarina Behrens <Katarina.Behrens@cib.de>

vcl/source/window/winproc.cxx

@@ -2098,9 +2098,15 @@ static void ImplHandleSalKeyMod( vcl::Window* pWindow, SalKeyModEvent* pEvent )
     }
 
     // #105224# send commandevent to allow special treatment of Ctrl-LeftShift/Ctrl-RightShift etc.
+    // + auto-accelerator feature, tdf#92630
 
+    vcl::Window *pChild = nullptr;
+
+    // Alt pressed or released => give SystemWindow a chance to handle auto-accelerator
+    if ( pEvent->mnCode == KEY_MOD2 || (pEvent->mnModKeyCode & MODKEY_MOD2) != 0 )
+    {
         // find window - first look to see if the system window is available
-    vcl::Window* pChild = pWindow->ImplGetWindowImpl()->mpFirstChild;
+        pChild = pWindow->ImplGetWindowImpl()->mpFirstChild;
 
         while ( pChild )
         {
@@ -2108,10 +2114,14 @@ static void ImplHandleSalKeyMod( vcl::Window* pWindow, SalKeyModEvent* pEvent )
                 break;
             pChild = pChild->ImplGetWindowImpl()->mpNext;
         }
+    }
+
     //...if not, try to find a key input window...
-    if (!pChild) ImplGetKeyInputWindow( pWindow );
+    if (!pChild)
+        pChild = ImplGetKeyInputWindow( pWindow );
     //...otherwise fail safe...
-    if (!pChild) pChild = pWindow;
+    if (!pChild)
+        pChild = pWindow;
 
     CommandModKeyData data( pEvent->mnModKeyCode );
     ImplCallCommand( pChild, CommandEventId::ModKeyChange, &data );