w3m tab browsing

No default keybinding for tab browsing. Pleaes configure following
function to appropriate keys:

  NEW_TAB      open new tab, clone current page
  TAB_LINK     open document refered by link in a new tab
               Num(N) + TAB_LINK will open in Nth tab
  TAB_GOTO     open URL in a new tab
               Num(N) + TAB_GOTO will open in Nth tab
  TAB_GOTO_RELATIVE
               open relative URL in a new tab
               Num(N) + TAB_GOTO_RELATIVE will open in Nth tab
  CLOSE_TAB    close current tab
               Num(N) + CLOSE_TAB will close Nth tab
  NEXT_TAB     change to next tab
               Num(N) + NEXT_TAB will change to Nth next tab
  PREV_TAB     change to prev tab
               Num(N) + PREV_TAB will change to Nth prev tab
  TAB_RIGHT    move current tab to right
               Num(N) + TAB_RIGHT will move current tab to N right
  TAB_LEFT     move current tab to left
               Num(N) + TAB_LEFT will move current tab to N left
  TAB_MENU     open tab selection menu
               operation in tab selection menu is same as operation 
		in buffer selection menu

You can operate with mouse

  left button .. 	move the tab if you click on the tab
		      	dragging a tab to another tab will move tab
			dragging a link to tab will open the link in the tab
			clicking on right upper `x' will current tab
  middle button ..	close the tab if you clink on the tab
  right button ..	open menu as usual

Options:

  open_tab_blank ...	open new tab if target is _blank or _new
			default: OFF
  close_tab_back ...	close the tab when you back from last buffer in the tab
			default: OFF (= Can't go back...)