Maxthon Browser doesn't seem to let you have icons only on the Favorites Bar.
Here's a little workaround:
Add a site to the Favorites Bar but don't edit the title, (yet)

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Once it's pinned, right click on it and choose Edit

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then give it a blank name by pressing and holding left Alt and enter 0160 on the numeric key pad, then release Alt, press Enter and click OK on the dialog. (You must have NumLock enabled for the Alt feature to work)

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If you attempt to give it a blank name whilst pinning it you'll get an error; you need to pin it with the default name then edit the name after as in step 2.

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