iconGrid: Add minRows/minColumns properties

When we adapt the grid to different display sizes,
we don't want the number of displayed items to get
too small. In the future we will scale down icons to
make sure that the grid fits add least minRows
x minColumns items, but for now we only take the
properties into account when calculating the dynamic spacing.

https://bugzilla.gnome.org/show_bug.cgi?id=706081

js/ui/appDisplay.js

@@ -30,6 +30,8 @@ const Util = imports.misc.util;
 const MAX_APPLICATION_WORK_MILLIS = 75;
 const MENU_POPUP_TIMEOUT = 600;
 const MAX_COLUMNS = 6;
+const MIN_COLUMNS = 4;
+const MIN_ROWS = 4;
 
 const INACTIVE_GRID_OPACITY = 77;
 const INACTIVE_GRID_OPACITY_ANIMATION_TIME = 0.15;
@@ -63,6 +65,8 @@ const BaseAppView = new Lang.Class({
     _init: function(params, gridParams) {
         gridParams = Params.parse(gridParams, { xAlign: St.Align.MIDDLE,
                                                 columnLimit: MAX_COLUMNS,
+                                                minRows: MIN_ROWS,
+                                                minColumns: MIN_COLUMNS,
                                                 fillParent: false });
         params = Params.parse(params, { usePagination: false });