Created attachment 78817 [details]
Fix patch for Bug 120441

Root case : On creation of the 2nd Spreadsheet document, a ScSimpleRefDlgWrapper object will be constructed. In its constructor, there are several lines of code cause this problem:
	if(bAutoReOpen && pViewShell)
		pWindow = pViewShell->CreateRefDialog( p, this, pInfo, pParentP, WID_SIMPLE_REF);

	if (!pWindow)
	{
		SC_MOD()->SetRefDialog( nId, sal_False );
	}
 The 2nd document does not have a reference picker dialog, so "SC_MOD()->SetRefDialog( nId, sal_False );" is executed, which clears ScModule's reference status.  This is an incorrect action, because the 1st document still has a reference dialog open, and ScModule should keep reference status while there are one document is in reference picking status.  On the 2nd document's creation, only its own reference status should be cleared, so we should call "pViewFrm->SetChildWindow( nId, sal_False );" instead of "SC_MOD()->SetRefDialog( nId, sal_False );". 
    Let's see other child dialog wrappers' constructor. In "ScAcceptChgDlgWrapper::ScAcceptChgDlgWrapper(...)", it is "pViewShell->GetViewFrame()->SetChildWindow( nId, sal_False );" not "SC_MOD()->SetRefDialog( nId, sal_False );". As a result, it does not cause this problem.
    Why "SC_MOD()->SetRefDialog( nId, sal_False );" cause frozen problem? Because once ScModule's reference picking status is cleared, when mouse is clicked on one cell in the 1st document, the ScModule does not think this is a reference picking action, and the ScModule thinks it is a normal mouse click on cell which will cause ScCellShell be activated and ScChartShell will be deactivated. As a result, reference picker dialog will be destroyed, and its parent dialog( Chart Range dialog ) will be set as foreground dialog. The original parent dialog of the Chart Range dialog is the CharWindow, but now the ChartWindow is destroyed when ScChartShell is deactivated, the ChartRange dialog will be reparented to ScGridWindow. in VCL, reparent a frame window will destroy the system window handle( HWND ), and recreated a new HWND. But the window position is not inherited from the original HWND, so when show the new window, system API "GetWindowRect" get rectangle as "Rectangle(0,0,0,0)". As a result, we can not see the new foreground ChartRange dialog, but it is a modal dialog whick locks the document, and the ScGridWindow can not respond to the user events. The document looks like frozen. By the way, we can not close the invisible foreground dialog (Chart Range dialog ) by pressing "Esc" key, because when this dialog is reparented to ScGridWindow VCL calls "ShowWindow( .., SW_NOACTVATE)", which means the foreground dialog does not get focus. It is a invisible modal dialog without focus, which locks the docuemt and can not be closed via "Esc" key.

I can't reproduct on AOO400m2(Build:9701)  -  Rev. 1489073 on Wind7 OS becasue fixed by comments 2