The CellImages property assigns multiple icons to a cell. The CellImage property assign a single icon to the cell. Instead if multiple icons need to be assigned to a single cell you have to use the CellImages property. The CellImages property takes a list of additional icons and display them in the cell. The list is separated by ','  and should contain numbers that represent indexes to Images list collection. Use the ItemFromPoint property to retrieve the part of the control being clicked. Use the CellHasCheckBox property to add a check box to a cell. Use the CellHasRadioButton property to assign a radio button to a cell. Use the CellPicture property to load a custom size picture to a cell. The Column.Def(exCellDrawPartsOrder) property specifies the order of the drawing parts for the entire column. By default, the parts are shows as check icon icons picture caption. The ImageSize property defines the size (width/height) of the icons within the control's Images collection. 

The following VB sample assigns the first and third icon to the cell:

With Gantt1.Items
        .CellImages(.ItemByIndex(0), 1) = "1,3"
End With

The following VB sample displays the index of icon being clicked:

Private Sub Gantt1_MouseUp(Button As Integer, Shift As Integer, X As Single, Y As Single)
    Dim i As HITEM, h As HitTestInfoEnum, c As Long
    With Gantt1
        i = .ItemFromPoint(X / Screen.TwipsPerPixelX, Y / Screen.TwipsPerPixelY, c, h)
    End With
    If (i <> 0) Then
        If exHTCellIcon = (h And exHTCellIcon) Then
            Debug.Print "The index of icon being clicked is: " & (h And &HFFFF0000) / 65536
        End If
    End If
End Sub

The following C++ sample assigns the first and the third icon to the cell:

#include "Items.h"
CItems items = m_gantt.GetItems();
items.SetCellImages( COleVariant( items.GetFocusItem() ), COleVariant( (long)0 ), COleVariant( "1,3" ) );

The following C++ sample displays the index of icon being clicked:

#include "Items.h"
void OnMouseUpGantt1(short Button, short Shift, long X, long Y) 
{
	CItems items = m_gantt.GetItems();
	long c = 0, hit = 0, h = m_gantt.GetItemFromPoint( X, Y, &c, &hit);
	if ( h != 0 )
	{
		if ( ( hit & 0x44 /*exHTCellIcon*/ ) == 0x44 )
		{
			CString strFormat;
			strFormat.Format( "The index of icon being clicked is: %i\n", (hit >> 16) );
			OutputDebugString( strFormat );
		}
	}
}

The following VB.NET sample assigns the first and the third icon to the cell:

With AxGantt1.Items
    .CellImages(.FocusItem, 0) = "1,3"
End With

The following VB.NET sample displays the index of icon being clicked:

Private Sub AxGantt1_MouseUpEvent(ByVal sender As Object, ByVal e As AxEXGANTTLib._IGanttEvents_MouseUpEvent) Handles AxGantt1.MouseUpEvent
    With AxGantt1
        Dim i As Integer, c As Integer, hit As EXGANTTLib.HitTestInfoEnum
        i = .get_ItemFromPoint(e.x, e.y, c, hit)
        If (Not (i = 0)) Then
            Debug.WriteLine("The index of icon being clicked is: " & (hit And &HFFFF0000) / 65536)
        End If
    End With
End Sub

The following C# sample assigns the first and the third icon to the cell:

axGantt1.Items.set_CellImages(axGantt1.Items.FocusItem, 0, "1,3");

The following C# sample displays the index of icon being clicked:

private void axGantt1_MouseUpEvent(object sender, AxEXGANTTLib._IGanttEvents_MouseUpEvent e)
{
	int c = 0;
	EXGANTTLib.HitTestInfoEnum hit;
	int i = axGantt1.get_ItemFromPoint(e.x, e.y, out c, out hit);
	if ((i != 0))
	{
		if ((Convert.ToUInt32(hit) & Convert.ToUInt32(EXGANTTLib.HitTestInfoEnum.exHTCellIcon)) == Convert.ToUInt32(EXGANTTLib.HitTestInfoEnum.exHTCellIcon))
		{
			string s = axGantt1.Items.get_CellCaption(i, c).ToString();
			s = "Cell: " + s + ", Icon's Index: " + (Convert.ToUInt32(hit) >> 16).ToString();
			System.Diagnostics.Debug.WriteLine(s);
		}
	}
}

The following VFP sample assigns the first and the third icon to the cell:

with thisform.Gantt1.Items
	.DefaultItem = .FocusItem
	.CellImages(0,0) = "1,3"
endwith

The following VFP sample displays the index of icon being clicked:

*** ActiveX Control Event ***
LPARAMETERS button, shift, x, y

local c, hit
c = 0
hit = 0
with thisform.Gantt1
	.Items.DefaultItem = .ItemFromPoint( x, y, @c, @hit )
	if ( .Items.DefaultItem <> 0 )
		if ( bitand( hit, 68 )= 68 )
			wait window nowait .Items.CellCaption( 0, c ) + " " + Str( Int((hit - 68)/65536) )
		endif
	endif
endwith

Add the code to the MouseUp, MouseMove or MouseDown event,