Use the HasButtonsCustom property to assign custom icons to the +/- signs on the parent items. The HasButtonsCustom property has effect only if the HasButtons property is exCustom. Use the Images, ReplaceIcon methods to add new icons to the control, at runtime. Use the HTMLPicture property to display icons in the node's caption. 

The following VB sample specifies different ( as in the screen shot ) +/- signs for the control:

 

With PropertiesList1
    .BeginUpdate
        .Images "gBJJgBAICAAGAAEAAQhYAf8Pf4hh0QihCJo2AEZjQAjEZFEaIEaEEaAIAkcbk0olUrlktl0vmExmUzmk1m03nE5nU7nk9n0/oFBoVDolFo1HpFJpVLplNp1PqFRqVTqlVq1XrFZrVbrldr1fsFhsVjslls1ntFptVrtltt1vuFxuVzul1u13vF5vV7vl9v1/wGBwWDwmFw2HxGJxWLxmNx2PyGRyWTymVy2XzGZzWbzmdz2f0Gh0WjwEWH0r08ekEikgAkso184iGkicPjcU2+zjW4jTnZ++jbv4Tvjbu4fF48adAv5fI4XO4ka4fRjO+4G73UZ3na7IAgI="
        .HasGridLines = exNoLines
        .HasButtons = exCustom
        .HasButtonsCustom(False) = 1
        .HasButtonsCustom(True) = 2
        .HTMLPicture("S1") = "gAAAABgYACEHgUJFEEAAWhUJCEJEEJggEhMCYEXjUbjkJQECj8gj8hAEjkshQEpADAlkJf8Cl8wl8xAEzmsxf85js7hL3jb4fCHjSPfCIoUJoAiREXogoFEJBFAPFPgQPoiCFBwqs5oshBD3O5/fFeP7/e5/kllP73eEJB7wf9LnkcnQAfkxeA/gTgB97A9+wErv8rAcYwuEw17w7ww75vs3gUBA"
        With .Add("I1", "", ReadOnly)
            .HTMLName = "S1 Item 1"
        End With
        With .Add("Subitem 1", "", Edit, , "I1")
        End With
        With .Add("Subitem 1.1", "", Edit, , "Subitem 1")
        End With
        With .Add("Subitem 2", "", Edit, , "I1")
        End With
    .EndUpdate
End With