GIFs are not supported. The way 3DGS handles animated images is to have all of the images side by side in the same image. You can also do animation in code like this:

Bmap img1 = <anim1.bmp>;
Bmap img2 = <anim2.bmp>;

Panel panel1 {
Bmap imgblank;
}

Function animation() {
Var I = 1;
While(1) {
If (i=2) {
Panel1.bmap = img2;
I =1;
}
If (i==1){
Panel1.bmap = img1;
I = 2;
}
Waitt(16);
}
}

Or something like that.