5:
How can I change the tooltip's visual appearance

EXTOOLTIPLib.ToolTip axToolTip1 = new EXTOOLTIPLib.ToolTip();
axToolTip1.VisualAppearance.Add(1,"c:\\exontrol\\images\\normal.ebn");
axToolTip1.Appearance = (EXTOOLTIPLib.AppearanceEnum)0x1000000;
axToolTip1.ShowToolTip("This is a tooltip that's shown with a different <b>visual apparance</b>.",null,null,null,null);

4:
How can I get the tooltip being semi-transparent

EXTOOLTIPLib.ToolTip axToolTip1 = new EXTOOLTIPLib.ToolTip();
axToolTip1.Transparency = 50;
axToolTip1.ShowToolTip("This is a tooltip that's shown with a different <b>visual apparance</b>.",null,null,null,null);

3:
How can I get displayed a picture inside the tooltip

EXTOOLTIPLib.ToolTip axToolTip1 = new EXTOOLTIPLib.ToolTip();
axToolTip1.set_HTMLPicture("pic1","c:\\exontrol\\images\\zipdisk.gif");
axToolTip1.ShowToolTip("<c><img>pic1</img><br>This is a bit of tooltip with a picture attached.",null,null,null,null);

2:
How can I get notified once the user clicks a hyperlink inside the tooltip

// AnchorClick event - Occurs when an anchor element is clicked.
private void axToolTip1_AnchorClick(object sender, AxEXTOOLTIPLib._IToolTipEvents_AnchorClickEvent e)
{
	System.Diagnostics.Debug.Print( "You have clicked the anchor" );
	System.Diagnostics.Debug.Print( e.anchorID.ToString() );
}
//this.axToolTip1.AnchorClick += new AxEXTOOLTIPLib._IToolTipEvents_AnchorClickEventHandler(this.axToolTip1_AnchorClick);

EXTOOLTIPLib.ToolTip axToolTip1 = new EXTOOLTIPLib.ToolTip();
axToolTip1.ShowToolTip("This is a bit of text that's displayed when <a A1>ShowToolTip</a> method is called.",null,null,null,null);

1:
How can I display the tooltip

EXTOOLTIPLib.ToolTip axToolTip1 = new EXTOOLTIPLib.ToolTip();
axToolTip1.ShowToolTip("This is a bit of text that's displayed when <b>ShowToolTip</b> method is called.",null,null,null,null);