By default, the BackColor property is 0. The property has no effect if it is 0. The BackColor property controls the background of the time scale unit being shown in the chart's header. Use the DrawTickLines property to specify whether the tick lines splits the time units in the chart's header. The BackColorChart property specifies the background color for the time scale unit being shown in the chart area ( not in the header ). Use the SplitBaseLevel property specifies whether the chart's base level gets divided when inside zoom are shown. The ForeColor property specifies the unit's foreground color. The PatternChartColor property determines the color to be used for pattern. 

Use the BackColor property to change the visual appearance for a time unit,  in the chart's header as in the following screen shot ( in red ):

 or when using a skin object the time-scale unit may show as follows:

The following VB sample shows how can I change the background color for a time unit:

With G2antt1
	.BeginUpdate 
	With .Chart
		.LevelCount = 2
		.FirstVisibleDate = #1/1/2008#
		.AllowInsideZoom = True
		.AllowResizeInsideZoom = False
		.InsideZoomOnDblClick = False
		.DefaultInsideZoomFormat.BackColor = 255
		With .InsideZooms
			.SplitBaseLevel = False
			.DefaultWidth = 18
			.Add(#1/4/2008#).AllowInsideFormat = False
		End With
	End With
	.EndUpdate 
End With

The following VB.NET sample shows how can I change the background color for a time unit:

With AxG2antt1
	.BeginUpdate 
	With .Chart
		.LevelCount = 2
		.FirstVisibleDate = #1/1/2008#
		.AllowInsideZoom = True
		.AllowResizeInsideZoom = False
		.InsideZoomOnDblClick = False
		.DefaultInsideZoomFormat.BackColor = 255
		With .InsideZooms
			.SplitBaseLevel = False
			.DefaultWidth = 18
			.Add(#1/4/2008#).AllowInsideFormat = False
		End With
	End With
	.EndUpdate 
End With

The following C++ sample shows how can I change the background color for a time unit:

/*
	Copy and paste the following directives to your header file as
	it defines the namespace 'EXG2ANTTLib' for the library: 'ExG2antt 1.0 Control Library'

	#import <ExG2antt.dll>
	using namespace EXG2ANTTLib;
*/
EXG2ANTTLib::IG2anttPtr spG2antt1 = GetDlgItem(IDC_G2ANTT1)->GetControlUnknown();
spG2antt1->BeginUpdate();
EXG2ANTTLib::IChartPtr var_Chart = spG2antt1->GetChart();
	var_Chart->PutLevelCount(2);
	var_Chart->PutFirstVisibleDate("1/1/2008");
	var_Chart->PutAllowInsideZoom(VARIANT_TRUE);
	var_Chart->PutAllowResizeInsideZoom(VARIANT_FALSE);
	var_Chart->PutInsideZoomOnDblClick(VARIANT_FALSE);
	var_Chart->GetDefaultInsideZoomFormat()->PutBackColor(255);
	EXG2ANTTLib::IInsideZoomsPtr var_InsideZooms = var_Chart->GetInsideZooms();
		var_InsideZooms->PutSplitBaseLevel(VARIANT_FALSE);
		var_InsideZooms->PutDefaultWidth(18);
		var_InsideZooms->Add("1/4/2008")->PutAllowInsideFormat(VARIANT_FALSE);
spG2antt1->EndUpdate();

The following C# sample shows how can I change the background color for a time unit:

axG2antt1.BeginUpdate();
EXG2ANTTLib.Chart var_Chart = axG2antt1.Chart;
	var_Chart.LevelCount = 2;
	var_Chart.FirstVisibleDate = "1/1/2008";
	var_Chart.AllowInsideZoom = true;
	var_Chart.AllowResizeInsideZoom = false;
	var_Chart.InsideZoomOnDblClick = false;
	var_Chart.DefaultInsideZoomFormat.BackColor = 255;
	EXG2ANTTLib.InsideZooms var_InsideZooms = var_Chart.InsideZooms;
		var_InsideZooms.SplitBaseLevel = false;
		var_InsideZooms.DefaultWidth = 18;
		var_InsideZooms.Add("1/4/2008").AllowInsideFormat = false;
axG2antt1.EndUpdate();

The following VFP sample shows how can I change the background color for a time unit:

with thisform.G2antt1
	.BeginUpdate
	with .Chart
		.LevelCount = 2
		.FirstVisibleDate = {^2008-1-1}
		.AllowInsideZoom = .T.
		.AllowResizeInsideZoom = .F.
		.InsideZoomOnDblClick = .F.
		.DefaultInsideZoomFormat.BackColor = 255
		with .InsideZooms
			.SplitBaseLevel = .F.
			.DefaultWidth = 18
			.Add({^2008-1-4}).AllowInsideFormat = .F.
		endwith
	endwith
	.EndUpdate
endwith