Problem with TextureData.Updates()

I'm using cimgui-go with a custom backend. Now I'm updating to version 1.4.0, and it seems to work until imgui wants to update the texures. The C code I'm translating from `imgui_impl_opengl3.cpp` is: for (ImTextureRect& r : tex->Updates) { const int src_pitch = r.w * tex->BytesPerPixel; bd->TempBuffer.resize(r.h * src_pitch); char* out_p = bd->TempBuffer.Data; for (int y = 0; y < r.h; y++, out_p += src_pitch) memcpy(out_p, tex->GetPixelsAt(r.x, r.y + y), src_pitch); IM_ASSERT(out_p == bd->TempBuffer.end()); GL_CALL(glTexSubImage2D(GL_TEXTURE_2D, 0, r.x, r.y, r.w, r.h, GL_RGBA, GL_UNSIGNED_BYTE, bd->TempBuffer.Data)); } My translation is: for _, r := range tex.Updates().Slice() { srcPitch := int(r.W()) * int(tex.BytesPerPixel()) size := int(r.H()) * srcPitch if len(renderer.tempBuffer) < size { renderer.tempBuffer = append(renderer.tempBuffer, make([]byte, size-len(renderer.tempBuffer))...) } offset := 0 for y := 0; y < int(r.H()); y++ { src := unsafe.Slice((*byte)(unsafe.Pointer(tex.PixelsAt(int32(r.X()), int32(r.Y())+int32(y)))), srcPitch) copy(renderer.tempBuffer[offset:offset+srcPitch], src) offset += srcPitch } gl.TexSubImage2D(gl.TEXTURE_2D, 0, int32(r.X()), int32(r.Y()), int32(r.W()), int32(r.H()), gl.RGBA, gl.UNSIGNED_BYTE, unsafe.Pointer(&renderer.tempBuffer[0])) } I get a fault panic on `copy`, which I think is due to strange rects from `tex.Updates().Slice()`: I get rectangles much larger than the texture or with width or height equal to 0.