Returns or sets the background color of the thumbnail boxes.
Image Thumbnail control
object.ThumbBackColor[=color]
Long
Use the RGB format. RGB (Red Green Blue) values range from 0 to 16,777,215 (&HFFFFFF). The high byte of a number in this range equals 0; the lower 3 bytes, from least to most significant byte, determine the amount of red, green, and blue, respectively. The red, green, and blue components are each represented by a number between 0 and 255 (&HFF).
The default value is dark gray -- RGB (128, 128, 128).
Do not confuse this property with the BackColor property, which sets the color for the control's entire background.
BackColor property
HighlightColor property