[Lazarus] Having more than 32 elements in a set (TGridOptions of TCustomGrid)

[Werner Pamler]

For fpspreadsheet I would like to implement the feature of Excel or 
Libre/OpenOffice that multiple cell ranges can be selected. The grid 
component in this package, TsSpreadsheetGrid, currently can select only 
a single range (if goRangeSelect is in the grid's Options) due to its 
inheritance from TCustomGrid.

My idea is to add a new "goMultiSelect" option to TCustomGrid directly 
since this might be an interesting feature for other applications as 
well, and then to write additional code to store multiple range 
rectangles. It shouldn't be too difficult, but I am failing already at 
the very first step: adding the new option to the type TGridOption. This 
is the new declaration:

type
   TGridOption = (
     goFixedVertLine,      // Ya
     goFixedHorzLine,      // Ya
     goVertLine,           // Ya
     goHorzLine,           // Ya
     goRangeSelect,        // Ya
     goDrawFocusSelected,  // Ya
     goRowSizing,          // Ya
     goColSizing,          // Ya
     goRowMoving,          // Ya
     goColMoving,          // Ya
     goEditing,            // Ya
     goAutoAddRows,        // JuMa
     goTabs,               // Ya
     goRowSelect,          // Ya
     goAlwaysShowEditor,   // Ya
     goThumbTracking,      // ya
     // Additional Options
     goColSpanning,        // Enable cellextent calcs
     goRelaxedRowSelect,   // User can see focused cell on goRowSelect
     goDblClickAutoSize,   // dblclicking columns borders (on hdrs) 
resize col.
     goSmoothScroll,       // Switch scrolling mode (pixel scroll is by 
default)
     goFixedRowNumbering,  // Ya
     goScrollKeepVisible,  // keeps focused cell visible while scrolling
     goHeaderHotTracking,  // Header cells change look when mouse is 
over them
     goHeaderPushedLook,   // Header cells looks pushed when clicked
     goSelectionActive,    // Setting grid.Selection moves also cell cursor
     goFixedColSizing,     // Allow to resize fixed columns
     goDontScrollPartCell, // clicking partially visible cells will not 
scroll
     goCellHints,          // show individual cell hints
     goTruncCellHints,     // show cell hints if cell text is too long
     goCellEllipsis,       // show "..." if cell text is too long
     goAutoAddRowsSkipContentCheck,//BB Also add a row (if AutoAddRows 
in Options) if last row is empty
     goRowHighlight,       // Highlight the current Row
     goMultiSelect         // Enable selection of multiple ranges <<<< NEW
   );
   TGridOptions = set of TGridOption;

Recompiling the package LCLBase fails with the error: "Property can't 
have a default value". I think this message is misleading and confusing 
because the true issue seems to me that the set of TGridOptions now 
contains 33 elements. In my understanding, the elements of a set 
correspond to the bits of an integer. In a 32-bit OS, therefore, a set 
can only contain 32 elements - there is one too many now...

Is this interpretation correct?

OK, here I could circumvent this issue by introducing a new boolean 
property "MultiSelect" which is evaluated when goRangeSelect is active. 
Maybe this is even better than the goMultiSelect option because it 
bypasses the conflict with goRangeSelect.

But what if I would not have this possibility? Is there a way to extend 
the set to more than 32 elements? If not, split the Options into groups 
of options like VirtualTreeView does? I fear the options of the grid 
components will require a major redsign soon.