Which control can I use to reproduce the look of the OutLook To-Do Bar?
I Tried using the ExplorerBar but I don't want to see the name of the group and still make it collapsable.
We don't have a control that emulates that behavior exactly; if you like you can submit a feature request along those lines.
I'm not sure I followed exactly why you did not want to use the ExplorerBar control as is, but you can hide the group text as it appears when it is collapsed by setting the UltraExplorerBar.GroupSettings.NavigationPaneCollapsedGroupAreaText to string.Empty.
I'd like to use the UltraExplorerBar, but I don't want to show the Groups since, all I will be having is one group which is the To-Do group.
Also, when collapse, it shows "Navigation Pane", is there a way to change that text?
You can have only one group and set NavigationPaneMaxGroupHeaders to 1. To change the text that is displayed when the navigation pane is collapsed, use UltraExplorerBar.GroupSettings.NavigationPaneCollapsedGroupAreaText, or UltraExplorerBarGroup.Settings.NavigationPaneCollapsedGroupAreaText.