Hello!

Very upset that the widget FolderView on the panel looks like a button and it is uncompromising.
Want to create an auto-hide panel with downloads folder, for example.
But the solution is not found.

Any ideas?

I'm afraid what you're after isn't supported by any of the default widgets shipped with Plasma Desktop.
Because the behaviour of the applet in a panel needs to be optimised for a specific use case (this can't be configured) it won't be possible to add this either i'm afraid.

very disappointing...
Strange for me, why it isn't done before.

is widget have different specifications or problems for desktop and panel, or its just develop with different displaying?

You could embed a dolphin window in this http://kde-apps.org/content/show.php/Ko ... ent=157471
It has however no "real" autohide capabilities but can be toggled with a shortcut (see documentation)

The default behaviour is for widgets to behave differently depending on their location - yes. In most cases this is what is desired, as panels aren't extremely large in size, limiting the amount of useful information which can be displayed in them.