[Frontend] Refactoring local controls hide and show

open #342
Now using CSS hover on pertinent plot areas;
Refining of select styling, tweaks for Firefox Linux;
Tweaks to local-control positioning in plots;
Changed *-options controls to use length > 1
instead of > 0;

platform/commonUI/general/res/sass/plots/_plots-main.scss

@@ -33,7 +33,22 @@ $plotDisplayArea: ($legendH + $interiorMargin, 0, $xBarH + $interiorMargin, $yBa
 	width: 100%;
 	height: 100%;
 
+    .gl-plot-local-controls {
+        @include trans-prop-nice(opacity, 150ms);
+        opacity: 0;
+        pointer-events: none;
+    }
+
+    .gl-plot-display-area,
+    .gl-plot-axis-area {
+        &:hover .gl-plot-local-controls {
+            opacity: 1;
+            pointer-events: inherit;
+        }
+    }
+
 	.gl-plot-axis-area {
+        //@include test();
 		position: absolute;
 		&.gl-plot-x {
 			top: auto;
@@ -114,15 +129,17 @@ $plotDisplayArea: ($legendH + $interiorMargin, 0, $xBarH + $interiorMargin, $yBa
 
 	.gl-plot-x-options,
     .gl-plot-y-options {
-		$h: 32px;
+		$h: 24px;
 		position: absolute;
-		height: auto;
+		height: $h;
 		min-height: $h;
         z-index: 2;
 	}
 
     .gl-plot-x-options {
-        top: $interiorMargin;
+        @include transform(translateX(-50%));
+        bottom: 0;
+        left: 50%;
     }
 
     .gl-plot-y-options {
@@ -132,6 +149,12 @@ $plotDisplayArea: ($legendH + $interiorMargin, 0, $xBarH + $interiorMargin, $yBa
         left: $yLabelW + $interiorMargin * 2;
     }
 
+    .t-plot-display-controls {
+        position: absolute;
+        top: $interiorMargin;
+        right: $interiorMargin;
+    }
+
 	.gl-plot-hash {
 		position: absolute;
 		border: 0 $colorPlotHash $stylePlotHash;