[VB6] - property reciving a strange values, when is used

[LaVolpe]

Negative values are usually VB system colors (i.e., vbButtonFace for example).
To convert a VB system color to a valid RGB color, you can use the GetSystColor API. The color code to pass to that api are stored in the 1st byte of the VB system color:

RGBcolor = GetSysColor(lngBorderSelectionColor And &HFF&)