options.snapOffset : when snapping, snap with this number in pixels as an offset

Author: lawrencepit

grid_and_snap_while_scrolling_example.html

@@ -99,6 +99,7 @@ <h1>Example of snapping to a grid while scrolling</h1>
           scrollInertia:0,
           mouseWheelPixels:19,
           snapAmount:19,
+          snapOffset: 1,
           scrollButtons:{
             enable:true,
             scrollType:"pixels",

jquery.mCustomScrollbar.js

@@ -35,6 +35,7 @@ along with this program.  If not, see http://www.gnu.org/licenses/.
 				autoDraggerLength:true, /*auto-adjust scrollbar dragger length: boolean*/
 				autoHideScrollbar:false, /*auto-hide scrollbar when idle*/
 				snapAmount:null, /* optional element always snaps to a multiple of this number in pixels */
+				snapOffset:0, /* when snapping, snap with this number in pixels as an offset */
 				scrollButtons:{ /*scroll buttons*/
 					enable:false, /*scroll buttons support: boolean*/
 					scrollType:"continuous", /*scroll buttons scrolling type: "continuous", "pixels"*/
@@ -126,6 +127,7 @@ along with this program.  If not, see http://www.gnu.org/licenses/.
 					"autoDraggerLength":options.autoDraggerLength,
 					"autoHideScrollbar":options.autoHideScrollbar,
 					"snapAmount":options.snapAmount,
+					"snapOffset":options.snapOffset,
 					"scrollButtons_enable":options.scrollButtons.enable,
 					"scrollButtons_scrollType":options.scrollButtons.scrollType,
 					"scrollButtons_scrollSpeed":options.scrollButtons.scrollSpeed,
@@ -678,7 +680,7 @@ along with this program.  If not, see http://www.gnu.org/licenses/.
 						}else{scrollTo=-scrollTo;}
 						var snapAmount = $this.data("snapAmount");
 						if (snapAmount) {
-							scrollTo = Math.round(scrollTo / snapAmount) * snapAmount;
+							scrollTo = Math.round(scrollTo / snapAmount) * snapAmount - $this.data("snapOffset");
 						}
 						/*scrolling animation*/
 						functions.mTweenAxis.call(this,mCSB_dragger[0],"left",Math.round(draggerScrollTo),draggerSpeed,options.scrollEasing);
@@ -717,7 +719,7 @@ along with this program.  If not, see http://www.gnu.org/licenses/.
 						}else{scrollTo=-scrollTo;}
 						var snapAmount = $this.data("snapAmount");
 						if (snapAmount) {
-							scrollTo = Math.round(scrollTo / snapAmount) * snapAmount;
+							scrollTo = Math.round(scrollTo / snapAmount) * snapAmount - $this.data("snapOffset");
 						}
 						/*scrolling animation*/
 						functions.mTweenAxis.call(this,mCSB_dragger[0],"top",Math.round(draggerScrollTo),draggerSpeed,options.scrollEasing);