message: Rendering issue fix
  Fixes ocornut/imgui#1172
diff: @@ -222,7 +222,7 @@ void ImDrawList::UpdateTextureID()
  // Try to merge with previous command if it matches, else use current command
  ImDrawCmd* prev_cmd = CmdBuffer.Size > 1 ? curr_cmd - 1 : NULL;
  - if (prev_cmd && prev_cmd->TextureId == curr_texture_id && memcmp(&prev_cmd->ClipRect, &GetCurrentClipRect(), sizeof(ImVec4)) == 0 && prev_cmd->UserCallback == NULL)
  + if (curr_cmd->ElemCount == 0 && prev_cmd && prev_cmd->TextureId == curr_texture_id && memcmp(&prev_cmd->ClipRect, &GetCurrentClipRect(), sizeof(ImVec4)) == 0 && prev_cmd->UserCallback == NULL)
  CmdBuffer.pop_back();
  else
  curr_cmd->TextureId = curr_texture_id;
  