The Layered Windows Plugin, layers.dll, tries to mimic tabbed windows. It keeps a stack of Windows in layers --- one on top of the other --- all with the same size and position. Switching to a new view is done by simply bringing a new window to front. By keeping all but one of the windows invisible the taskbar is kept clutter-free. Even though you still have as many browser windows as usually.. the result is an illusion that may or may not fool you.
More traditional implementations of "Tabs" are made in the main application. By encapsulating the rendering engine, and use it as a component, they can then give the renderer any graphics area to draw the pages at. Since the "Layers" have been added through a plugin this not an option. K-Meleon will still give Gecko, the Mozilla rendering engine, the full client area of a browser window to draw pages at. The layers plugin listens to messages passing by the browser window, hijacks some of them and issues a few new ones, and that way keeps the windows at the same position with only one of them visible at any time. Biggest benefit with this approach is that the K-Meleon core had not to be changed to support tab-like browsing. With the plugin disabled there is no traces of it in form of memory or CPU usage.
With the layers plugin enabled you can have a menu with all layers of the current window and choose from the list what layer to switch to. This looks and behaves a bit like an MDI with all sub-windows maximized. There is also a buttonbar that can be activated and styled at wish. This gives a more tab-like behavior. Finally the plugin offers the layers(next), layers(prev), layers(last) and layers(X) functions as means to switch layer; bind them to any keys you want.
With the default settings (Accel.cfg) ... Ctrl-T, Ctrl-W, Ctrl-F4, Ctrl-Tab, Ctrl-Shift-Tab, ... See the accelerator configuration reference for layers.
Layers menu (Menus.cfg). See the menu configuration reference for layers.
The layers buttonbar can be toggled on or off by the View->Toolbars->Layers menu choice, or by setting the kmeleon.plugin.layers.rebar preference. To configure the look of the layers buttonbar and buttons see the kmeleon.plugin.layers.title, kmeleon.plugin.layers.width, kmeleon.plugin.layers.style, and kmeleon.plugin.layers.numbers preferences. Right clicking on a layer button brings up the menu defined as LayerButtonPopup (Menus.cfg).
There is no way to add configurable graphical buttons to the layers bar, nor are there any toolbar buttons for layers on the default toolbar. You can either add your buttons to the main toolbar or build a new toolbar for your graphical buttons by editing the toolbars.cfg file. See the toolbar configuration reference for layers.