Expand use of generators in SDI test

[KeyWorksRW]

Description:

The new Unused testing dialog reveals that we have 22 generators not currently being used in the SDI testing app. This is the current list:

• [x] Check3State
• [x] StaticRadioBtnBoxSizer
• [x] ribbonSeparator
• [x] tool_dropdown
• [x] toolSeparator
• [x] toolStretchable
• [x] wxActivityIndicator
• [x] wxCollapsiblePane
• [ ] wxDataViewListCtrl
• [ ] wxDataViewTreeCtrl
• [x] wxPropertyGrid
• [x] wxFileCtrl
• [ ] wxGenericDirCtrl
• [x] wxGridSizer
• [ ] wxScrolledCanvas
• [x] wxStaticLine
• [ ] wxScrolledWindow
• [ ] wxTreeCtrl
• [ ] wxTreeCtrlBase
• [ ] wxTreeListCtrl
• [ ] wxWebView