Sets the image assigned to index, idx.
With overloads 2 and 3 the srcImage bitmap is copied internally; therefore you can free srcImage after calling SetImage.
With overload 4 the image can be a local file or web page based image.
With overloads 3 and 4 use SourceImageIndex to specify the image index if the source file is a multi-frame file (such as a TIFF or AVI). You can also specify the FileFormat if it cannot be determined by the file extension or content.