# NOTE: To use bitmap masks, the flag ILC_MASK (0x0001) must be set.
#  Also, using a 16 color bmp seem to require ILC_COLOR16 (0x0010)
my $il = Win32::GUI::ImageList->new(16, 16, 0x0011, 4, 5);

# This Will NOW use masked BMP images
$il->Add('FolderOpen.bmp', 'FolderOpenMask.bmp');
$il->Add('FolderClosed.bmp', 'FolderClosedMask.bmp');