The three DataTable *Selected methods report wrong selection location when caused by mouse selection

[davep]

This was first raised by a user on our Discord server, and in testing the issue some more with this code:

from textual.app        import App, ComposeResult
from textual.containers import Vertical
from textual.widgets    import Header, Footer, TextLog, DataTable
from textual.binding    import Binding

class TestDataTable( App[ None ] ):

    BINDINGS = [
        Binding( "c", "cursor( 'cell' )", "Cell" ),
        Binding( "r", "cursor( 'row' )", "Row" ),
        Binding( "o", "cursor( 'column' )", "Column" ),
    ]

    CSS = """
    DataTable {
        height: 1fr;
        border: round green;
    }

    DataTable:focus {
        border: double green;
    }

    TextLog {
        height: 1fr;
        border: round red;
    }

    TextLog:focus {
        border: double red;
    }
    """

    def compose(self) -> ComposeResult:
        yield Header()
        self.dt = DataTable()
        yield Vertical( self.dt, TextLog() )
        yield Footer()

    def on_mount(self) -> None:
        self.dt.cursor_type = "row"
        self.dt.add_columns( "Row", *[ f"Column {n+1}" for n in range( 10 ) ] )
        for row in range( 50 ):
            self.dt.add_row( *[ str( row ), *[ str( n ) for n in range( 10 ) ] ] )
        self.dt.focus()

    def action_cursor( self, cursor: str ) -> None:
        self.dt.cursor_type = cursor

    def on_data_table_cell_highlighted( self, event: DataTable.CellHighlighted ) -> None:
        self.query_one( TextLog ).write( event )

    def on_data_table_cell_selected( self, event: DataTable.CellSelected ) -> None:
        self.query_one( TextLog ).write( event )

    def on_data_table_row_selected( self, event: DataTable.RowSelected ) -> None:
        self.query_one( TextLog ).write( event )

    def on_data_table_row_highlighted( self, event: DataTable.RowHighlighted ) -> None:
        self.query_one( TextLog ).write( event )

    def on_data_table_column_selected( self, event: DataTable.ColumnSelected ) -> None:
        self.query_one( TextLog ).write( event )

    def on_data_table_column_highlighted( self, event: DataTable.ColumnHighlighted ) -> None:
        self.query_one( TextLog ).write( event )

if __name__ == "__main__":
    TestDataTable().run()

it appears that if a *Selected event is initiated from the keyboard, everything works fine. On the other hand, if a *Selected event is initiated by a mouse click, the resulting event object will refer to the cell/row/column that was selected before the click took place, not the one that was clicked on.

Tested with both 0.10.1 and main.

[darrenburns]

I've got the fix for this in #1638.

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