Improving the functionality of comboboxes in wxGrid

The grid in wxWidgets  allows you to insert a combobox in a cell, which is a feature that very few other toolkits offer.
However, the default behaviour is somewhat lacking.
First of all, there is no visual indication of which cell has a combox until the cell has focus.
Then, when you click on a cell to edit it you have to click three times: once to give the cell focus, once to activate the editor and a third to actaully open the combobox. Not very user friendly if you have a few dozen items to edit.
I wrote some classes to rectify these problems:

displays the combobox buttons when not active.
activates cells in the grid with just one click
Opens the comboxbox immediately if you clicked on the button

To use this code include the files in this zip file in your project:

Then insert the combobox into the cell like this:
#include "EzGrid.h"
#include "wxgridcellcombobox.h"
EzGrid *grid;
grid = new EzGrid( this, -1, wxPoint( 0, 0 ), wxSize( 400, 300 ) );
grid->CreateGrid( 4, 4 );   
grid->SetCellRenderer(1, 1, new wxGridCellChoiceRenderer);

wxString strChoices[3] = {"one", "two", "three"};;
grid->SetCellEditor(1, 1, new wxFastComboEditor(3, strChoices, TRUE));

ExGrid will put all cells into edit mode with just one click, not just the comboboxes. Normally this is desirable because you can edit the cells quicker.
The code works under both Windows and Linux (wxGTK), except for the code that opens the combobox automatically. I'm not very experienced in GTK and I haven't yet figured out how to send a left mouse click message to a control.