Dear Curaga,
TinyCore Linux 8.0 x86 32bit image (iso's md5 f7fee34a73a7f8e3adb30778c7c32c51) downloaded from the cite.
It's fltk-1.3.tcz (md5: 6d342fa56...) exports (I will skip all unrelated to items):
$nm -D /usr/local/lib/libfltk.so.1.3 | grep Fl_Image
00043b70 T _ZN8Fl_Image10desaturateEv ; Fl_Image::desaturate()
00044192 T _ZN8Fl_Image10draw_emptyEii ; Fl_Image::draw_empty(int, int)
00044240 T _ZN8Fl_Image11RGB_scalingE14Fl_RGB_Scaling ; Fl_Image::RGB_scaling(Fl_RGB_Scaling)
0004425a T _ZN8Fl_Image11RGB_scalingEv ; Fl_Image::RGB_scaling()
000b78ec B _ZN8Fl_Image12RGB_scaling_E ; Fl_Image::RGB_scaling_
00043b6a T _ZN8Fl_Image13color_averageEjf ; Fl_Image::color_average(unsigned int, float)
00043c16 T _ZN8Fl_Image4copyEii ; Fl_Image::copy(int, int)
00044218 T _ZN8Fl_Image4drawEiiiiii ; Fl_Image::draw(int, int, int, int, int, int)
00043c6c T _ZN8Fl_Image5labelEP12Fl_Menu_Item ; Fl_Image::label(Fl_Menu_Item*)
00043b76 T _ZN8Fl_Image5labelEP9Fl_Widget ; Fl_Image::label(Fl_Widget*)
00043b84 T _ZN8Fl_Image7measureEPK8Fl_LabelRiS3_ ; Fl_Image::measure(Fl_Label const*, int&, int&)
00043b70 T _ZN8Fl_Image7uncacheEv ; Fl_Image::uncache()
00044102 T _ZN8Fl_Image9labeltypeEPK8Fl_Labeliiiij ; Fl_Image::labeltype(Fl_Label const*, int, int, int, int, unsigned int)
00043be8 T _ZN8Fl_ImageD0Ev ;Fl_Image::~Fl_Image()
00043b64 T _ZN8Fl_ImageD1Ev ;Fl_Image::~Fl_Image()
000b38a0 V _ZTV8Fl_Image ;vtable for Fl_Image
$nm -D /usr/local/lib/libfltk.so.1.3 | grep Fl_RGB_Image
00043d80 T Fl_RGB_Image::desaturate()
00043ed4 T Fl_RGB_Image::color_average(unsigned int, float)
00044272 T Fl_RGB_Image::copy(int, int)
00043b9e T Fl_RGB_Image::draw(int, int, int, int, int, int)
00043c6c T Fl_RGB_Image::label(Fl_Menu_Item*)
00043bda T Fl_RGB_Image::label(Fl_Widget*)
00043ca6 T Fl_RGB_Image::uncache()
000b5358 D Fl_RGB_Image::max_size_
000448f6 T Fl_RGB_Image::Fl_RGB_Image(Fl_Pixmap const*, unsigned int)
000448f6 T Fl_RGB_Image::Fl_RGB_Image(Fl_Pixmap const*, unsigned int)
00043d52 T Fl_RGB_Image::~Fl_RGB_Image()
00043cfc T Fl_RGB_Image::~Fl_RGB_Image()
00043cfc T Fl_RGB_Image::~Fl_RGB_Image()
000b38cc V vtable for Fl_RGB_Image
So - there are no constructors Fl_Image::Fl_Image(int, int, int) "_ZN8Fl_ImageC1Eiii" and Fl_RGB_Image::Fl_RGB_Image(unsigned char const*, int, int, int, int) "_ZN12Fl_RGB_ImageC1EPKhiiii".
But when installed fltk-full.tcz (md5sum starts 5a25) and its libfltk.so.1.3 (md5sum starts with 799)
$nm -D /usr/local/lib/libfltk.so.1.3 | grep Fl_ImageC
0004b570 T _ZN8Fl_ImageC1Eiii Fl_Image::Fl_Image(int, int, int)
0004b570 T _ZN8Fl_ImageC2Eiii : Fl_Image::Fl_Image(int, int, int)
$nm -D /usr/local/lib/libfltk.so.1.3 | grep Fl_RGB_ImageC
0004b6f6 T _ZN12Fl_RGB_ImageC1EPKhiiii ; Fl_RGB_Image::Fl_RGB_Image(unsigned char const*, int, int, int, int)