Merge master fix

src/c3.axis.js

@@ -176,8 +176,15 @@ function c3_axis(d3, isCategory) {
         return axis;
     };
     axis.tickValues = function (x) {
-        if (!arguments.length) { return tickValues; }
-        tickValues = x;
+        if (typeof x === 'function') {
+            tickValues = function () {
+                return x(scale.domain());
+            };
+        }
+        else {
+            if (!arguments.length) { return tickValues; }
+            tickValues = x;
+        }
         return axis;
     };
     return axis;

src/shape.js

@@ -169,9 +169,12 @@ c3_chart_internal_fn.generateDrawArea = function (areaIndices, isSub) {
         };
 
     area = config[__axis_rotated] ? area.x0(value0).x1(value1).y(xValue) : area.x(xValue).y0(value0).y1(value1);
+    if (!config[__line_connect_null]) {
+        area = area.defined(function (d) { return d.value !== null; });
+    }
 
     return function (d) {
-        var data = $$.filterRemoveNull(d.values), x0 = 0, y0 = 0, path;
+        var data = config[__line_connect_null] ? $$.filterRemoveNull(d.values) : d.values, x0 = 0, y0 = 0, path;
         if ($$.isAreaType(d)) {
             path = area.interpolate($$.getInterpolate(d))(data);
         } else {

src/tooltip.js

@@ -84,7 +84,7 @@ c3_chart_internal_fn.showTooltip = function (selectedData, mouse) {
         if (tooltipRight > chartRight) {
             tooltipLeft -= tooltipRight - chartRight;
         }
-        if (tooltipTop + tHeight > $$.getCurrentHeight()) {
+        if (tooltipTop + tHeight > $$.getCurrentHeight() && tooltipTop > tHeight + 30) {
             tooltipTop -= tHeight + 30;
         }
     }