select multiple cells in MSHFlexGrid

[Ron22]

I have a program and need to select multible cells in a HSHFlexGrid.
I have it working the the folloing code with some issues
Here is what I want I want to select mulitble cells but only one cell per col I must be able to know what cells are picked later.
The problems are is there a better way to set the cellbackcolor? Stepping thou all cells take long on some larger grids. I have the backcollor changed depending on what is in there so I can not globaly set all backcolor.
Is there a better way to do what I am trying?
Is there a faster way to clear the cell backcolor?

Dim multi As Boolean
Dim TargetSelect(200) As Integer  ' max cols possible
 
Private Sub MSHFlexGrid1_MouseDown(Button As Integer, Shift As Integer, x As Single, y As Single)
' do not want row or col 0
If MSHFlexGrid1.MouseCol > 0 And MSHFlexGrid1.MouseRow > 0 Then
    If Button = vbLeftButton Then
        Dim lngColor As Long
        If Shift = vbCtrlMask Then
           ' Only one want cell allowed per col 
           If TargetSelect(MSHFlexGrid1.Col) < 1 Then
                lngColor = MSHFlexGrid1.BackColor
                If MSHFlexGrid1.CellBackColor = MSHFlexGrid1.BackColor Then
                    lngColor = MSHFlexGrid1.BackColorSel
                    TargetSelect(MSHFlexGrid1.Col) = 0
                End If
                With MSHFlexGrid1
                    .CellBackColor = lngColor
                     ' save what cell is marked in this col
                    TargetSelect(.Col) = .Row
                End With
                mulit = True
            End If
            
        Else
            If multi = True Then
              lngColor = MSHFlexGrid1.BackColor       
              With MSHFlexGrid1
                tmprow = .Row
                tmpcol = .Col
                ' Take too long!
                For a = 1 To .Cols - 1
                    .Col = a
                    TargetSelect(.Col) = 0
                    For b = 1 To .Rows - 1
                        .Row = b
                        If .CellBackColor = .BackColorSel Then
                            ' Set all cell back to normal
                            .CellBackColor = lngColor
                        End If
                    Next b
                Next a
                .Row = tmprow
                .Col = tmpcol
              End With
           End If
            
           lngColor = MSHFlexGrid1.BackColor
    
           If MSHFlexGrid1.CellBackColor = MSHFlexGrid1.BackColor Then
                lngColor = MSHFlexGrid1.BackColorSel
                TargetSelect(MSHFlexGrid1.Col) = 0
           End If
    
           With MSHFlexGrid1
                .CellBackColor = lngColor
                TargetSelect(.Col) = .Row
           End With
            
           multi = True
        
        End If
    
    End If
 
End If
End Sub