addEventHandler("onClientResourceStart", resourceRoot,
    function()
        wnd = guiCreateWindow(455, 191, 425, 227, "", false)
        guiWindowSetSizable(wnd, false)
        butt1 = guiCreateButton(14, 30, 133, 32, "deagle", false, wnd)
        butt2 = guiCreateButton(199, 38, 150, 34, "shotgun", false, wnd)
		butt3 = guiCreateButton(300, 10, 150, 34, "2", false, wnd)
        ebox = guiCreateEdit(139, 111, 182, 45, "", false, wnd) 
		
		 addEventHandler( "onClientGUIClick", butt1, function()
		 if (source==butt1) then
		slot1= tostring(guiGetText (ebox)) 
		bindKey(slot1,"down",function()
		cslot1= getPedWeaponSlot ( localPlayer )
		if ((2-cslot1) > 0) then
		for i =1,(2-cslot1) do
		setControlState ( "next_weapon", true )
		outputChatBox("next_fail")
		end
		elseif((2-cslot1)<0) then
		for i =1,(cslot1-2) do
		setControlState ( "previous_weapon", true )
		outputChatBox("pre_fail")
		end
			
		end
		end)
		end
		end)
		end)
	that's when i tried "next_weapon" control.
 
addEventHandler("onClientResourceStart", resourceRoot,
    function()
        wnd = guiCreateWindow(455, 191, 425, 227, "", false)
        guiWindowSetSizable(wnd, false)
        butt1 = guiCreateButton(14, 30, 133, 32, "deagle", false, wnd)
        butt2 = guiCreateButton(199, 38, 150, 34, "shotgun", false, wnd)
		butt3 = guiCreateButton(300, 10, 150, 34, "2", false, wnd)
        ebox = guiCreateEdit(139, 111, 182, 45, "", false, wnd) 
		
		 addEventHandler( "onClientGUIClick", butt1, function()
		 if (source==butt1) then
		slot1= tostring(guiGetText (ebox)) 
		bindKey(slot1,"down",function()
		setPedWeaponSlot (localPlayer,2)
		end)
		end
		end)
		addEventHandler( "onClientGUIClick", butt2, function()
		 if (source==butt2) then
		slot2= tostring(guiGetText (ebox)) 
		bindKey(slot2,"down",function()
		setPedWeaponSlot (localPlayer,3)
		end)
		end
		end)
		
		
		end)
	that one when i tried to bind one key for 2 functions 
	only the 2nd entered function will work.