== Introduction ==

You can set the tooltip for a wxGrid window as a whole using the
SetToolTip method, but how do you set different tooltips for
individual cells of the grid? 

Here's how: Have a mouse event check every mouse move to see if you've
moved between cells, and change the tooltip when you have.

== The Code ==

Here's a function to do the hard work.  Pass the grid along with a
callback which takes row and column parameters and returns a tooltip
string for that cell.  InstallGridHint will do the rest.

{{{
#!python

def InstallGridHint(grid, rowcolhintcallback):
    prev_rowcol = [None,None]
    def OnMouseMotion(evt):
	# evt.GetRow() and evt.GetCol() would be nice to have here,
	# but as this is a mouse event, not a grid event, they are not
	# available and we need to compute them by hand.
        x, y = grid.CalcUnscrolledPosition(evt.GetPosition())
        row = grid.YToRow(y)
        col = grid.XToCol(x)

        if (row,col) != prev_rowcol and row >= 0 and col >= 0:
            prev_rowcol[:] = [row,col]
            hinttext = rowcolhintcallback(row, col)
            if hinttext is None:
                hinttext = ''
            grid.GetGridWindow().SetToolTipString(hinttext)
        evt.Skip()
        
    wx.EVT_MOTION(grid.GetGridWindow(), OnMouseMotion)
}}}