Today the "Save as..." is available topbar menu:

and in right-click context menu

This has many problems:

• We can not save as .mhtml
• The contextual menu part comes in conflict with saving a resources (images, videos, ...)

We should:

• Keep only the topbar menu
• In the dialog we should be able to choose the .mhtml format (at the top bottom selector of the file picker) amd save in .mhtml