add dragmode pan button to mapbox modebar

- and set dragmode to 'pan' in fullLayout when its value is coerced
  to 'zoom' so the corresponding modebar button is correctly
  highlighted.
- do this until dragmode 'zoom' (i.e. a zoombox like behavior)
  is implemented.

Author: etpinard

Diff for: src/components/fx/layout_defaults.js

@@ -28,6 +28,14 @@ module.exports = function supplyLayoutDefaults(layoutIn, layoutOut, fullData) {
     else hovermodeDflt = 'closest';
 
     coerce('hovermode', hovermodeDflt);
+
+    // if only mapbox subplots is present on graph,
+    // reset 'zoom' dragmode to 'pan' until 'zoom' is implemented,
+    // so that the correct modebar button is active
+    if(layoutOut._has('mapbox') && layoutOut._basePlotModules.length === 1 &&
+       layoutOut.dragmode === 'zoom') {
+        layoutOut.dragmode = 'pan';
+    }
 };
 
 function isHoriz(fullData) {

Diff for: src/components/modebar/manage.js

@@ -11,6 +11,7 @@
 
 var Axes = require('../../plots/cartesian/axes');
 var scatterSubTypes = require('../../traces/scatter/subtypes');
+var Registry = require('../../registry');
 
 var createModeBar = require('./modebar');
 var modeBarButtons = require('./buttons');
@@ -78,7 +79,8 @@ function getButtonGroups(gd, buttonsToRemove, buttonsToAdd) {
         hasGeo = fullLayout._has('geo'),
         hasPie = fullLayout._has('pie'),
         hasGL2D = fullLayout._has('gl2d'),
-        hasTernary = fullLayout._has('ternary');
+        hasTernary = fullLayout._has('ternary'),
+        hasMapbox = fullLayout._has('mapbox');
 
     var groups = [];
 
@@ -121,6 +123,9 @@ function getButtonGroups(gd, buttonsToRemove, buttonsToAdd) {
     if(((hasCartesian || hasGL2D) && !allAxesFixed) || hasTernary) {
         dragModeGroup = ['zoom2d', 'pan2d'];
     }
+    if(hasMapbox) {
+        dragModeGroup = ['pan2d'];
+    }
     if(isSelectable(fullData)) {
         dragModeGroup.push('select2d');
         dragModeGroup.push('lasso2d');

Diff for: test/jasmine/tests/mapbox_test.js

@@ -1,4 +1,5 @@
 var Plotly = require('@lib');
+var Plots = require('@src/plots/plots');
 var Lib = require('@src/lib');
 
 var constants = require('@src/plots/mapbox/constants');
@@ -31,7 +32,7 @@ describe('mapbox defaults', function() {
     beforeEach(function() {
         layoutOut = { font: { color: 'red' } };
 
-        // needs a ternary-ref in a trace in order to be detected
+        // needs a mapbox-ref in a trace in order to be detected
         fullData = [{ type: 'scattermapbox', subplot: 'mapbox' }];
     });
 
@@ -170,6 +171,16 @@ describe('mapbox defaults', function() {
         expect(layoutOut.mapbox.layers[3].fill).toBeUndefined();
         expect(layoutOut.mapbox.layers[3].circle).toBeUndefined();
     });
+
+    it('should set *layout.dragmode* to pan while zoom is not available', function() {
+        var gd = {
+            data: fullData,
+            layout: {}
+        };
+
+        Plots.supplyDefaults(gd);
+        expect(gd._fullLayout.dragmode).toBe('pan');
+    });
 });
 
 describe('mapbox credentials', function() {