ImDrawList: Fixed a (rarely occuring) bug with merging with previous command + unnecessary OverlayDrawList command

imgui.cpp

@@ -2066,7 +2066,6 @@ void ImGui::NewFrame()
     g.OverlayDrawList.Clear();
     g.OverlayDrawList.PushTextureID(g.IO.Fonts->TexID);
     g.OverlayDrawList.PushClipRectFullScreen();
-    g.OverlayDrawList.AddDrawCmd();
 
     // Mark rendering data as invalid to prevent user who may have a handle on it to use it
     g.RenderDrawData.Valid = false;

imgui_draw.cpp

@@ -196,7 +196,7 @@ void ImDrawList::UpdateClipRect()
 
     // 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 && memcmp(&prev_cmd->ClipRect, &curr_clip_rect, sizeof(ImVec4)) == 0 && prev_cmd->TextureId == GetCurrentTextureId() && prev_cmd->UserCallback == NULL)
+    if (curr_cmd->ElemCount == 0 && prev_cmd && memcmp(&prev_cmd->ClipRect, &curr_clip_rect, sizeof(ImVec4)) == 0 && prev_cmd->TextureId == GetCurrentTextureId() && prev_cmd->UserCallback == NULL)
         CmdBuffer.pop_back();
     else
         curr_cmd->ClipRect = curr_clip_rect;