awful.tag: setters have low and high bounding values

Signed-off-by: Julien Danjou <julien@danjou.info>

lib/awful/tag.lua.in

@@ -103,9 +103,11 @@ end
 -- @param mwfact Master width factor.
 function setmwfact(mwfact, t)
     local t = t or selected()
+    if mwfact >= 0 and mwfact <= 1 then
         setproperty(t, "mwfact", mwfact)
         capi.hooks.arrange()(t.screen)
     end
+end
 
 --- Increase master width factor.
 -- @param add Value to add to master width factor.
@@ -125,9 +127,11 @@ end
 -- @param t Optional tag.
 function setnmaster(nmaster, t)
     local t = t or selected()
+    if nmaster >= 0 then
         setproperty(t, "nmaster", nmaster)
         capi.hooks.arrange()(t.screen)
     end
+end
 
 --- Get the number of master windows.
 -- @param t Optional tag.
@@ -163,9 +167,11 @@ end
 -- @param ncol The number of column.
 function setncol(ncol, t)
     local t = t or selected()
+    if ncol >= 1 then
         setproperty(t, "ncol", ncol)
         capi.hooks.arrange()(t.screen)
     end
+end
 
 --- Get number of column windows.
 -- @param t Optional tag.