Maxthon has a toolbar autohide feature, where everything hides except for the tabs, would it be possible to get something similar with K-Meleon?

Yes - maybe have a look at menu bar? and what it does. I think that is similar.

i mean the tool bar with that name - it was used as only visible item with k-ninja.
Some even configured it to be only visible on demand.

Hmm, I don't see "Menu Bar" listed in my Toolbar options.

go View/Toolbars/ activate Menu Bar
- C /experiment what other bars You want. (layers! probably - but what else?
cut out rest for trial.).

Next: there are items in pref.js that can be set via user.js & needs restart.
user_pref("kmeleon.toolband.Menu.visibility", false);
this will afaik get rid of normal menu.

that can be probably also altered via URL " about:config " & ENTER

AFAIK: Walt did a hack that is similar to what You want. jsnj gave help.
If I did not remember items right - repost Your question in General.
AFAIK we have this as normal oportunity.
We have few devs - but much we can do ourselves.

Actually you are trying to re-invent K-Ninja
Under the menu item View -> Toolbars -> Menu/Throbber
you should be able to access the file user.js
Then you can change the following line
user_pref("kmeleon.toolband.Menu.visibility", true);
and make it FALSE
user_pref("kmeleon.toolband.Menu.visibility", false);
then restart and you should be in business
but please do me a favor
try pushing the keys
Alt + V
to activate the View menu, so that you will know how to
work from the menu after it becomes invisible

If you go to your skins folder and find the active skin
for example in my current k-meleon:
... skins\Phoenity\

and then find the toolbars config file
in my case:
... skins\Phoenity\toolbars.cfg

and edit it in a text editor to change the reload button
on the main toolbar (which can have various names, depending ...)
so that you will always have a menu available
which in my case means changing this:

Reload {
ID_NAV_RELOAD|Reload Options
Reload page. Right-click for more options.

so that it looks more like this:

Reload {
ID_NAV_RELOAD|Compact Menu
Reload page. Right-click for Compact Menu.


Note: You could use other buttons but the reload button is available on all k-meleons.
You could also use the main menu, which I think would be like this:
ID_NAV_RELOAD|Main
but I would recommend the Compact Menu (it is available on most k-meleons)

In that same toolbars config file
in my case:
... skins\Phoenity\toolbars.cfg

(and in general in all ".cfg" files within k-meleon) you can use pound signs (the hash marks: "#") to remove any button you don't want to use
as in my case:

# %ifplugin history

# History {
# History(View)|History
# View History. Right-click for more options.
# mainbarhot.bmp[7]
# mainbarcold.bmp[7]
# mainbarcold.bmp[7]
# }

# %endif

# Print{
# ID_FILE_PRINT|Print
# Print. Right-click for more options.
# mainbarhot.bmp[8]
# mainbarcold.bmp[8]
# mainbarcold.bmp[8]
# }