    /**
     * @class Ext.layout.container.Column
     * @extends Ext.layout.container.Auto
     * <p>This is the layout style of choice for creating structural layouts in a multi-column format where the width of
     * each column can be specified as a percentage or fixed width, but the height is allowed to vary based on the content.
     * This class is intended to be extended or created via the layout:'column' {@link Ext.container.Container#layout} config,
     * and should generally not need to be created directly via the new keyword.</p>
     * <p>ColumnLayout does not have any direct config options (other than inherited ones), but it does support a
     * specific config property of <b><tt>columnWidth</tt></b> that can be included in the config of any panel added to it.  The
     * layout will use the columnWidth (if present) or width of each panel during layout to determine how to size each panel.
     * If width or columnWidth is not specified for a given panel, its width will default to the panel's width (or auto).</p>
     * <p>The width property is always evaluated as pixels, and must be a number greater than or equal to 1.
     * The columnWidth property is always evaluated as a percentage, and must be a decimal value greater than 0 and
     * less than 1 (e.g., .25).</p>
     * <p>The basic rules for specifying column widths are pretty simple.  The logic makes two passes through the
     * set of contained panels.  During the first layout pass, all panels that either have a fixed width or none
     * specified (auto) are skipped, but their widths are subtracted from the overall container width.  During the second
     * pass, all panels with columnWidths are assigned pixel widths in proportion to their percentages based on
     * the total <b>remaining</b> container width.  In other words, percentage width panels are designed to fill the space
     * left over by all the fixed-width and/or auto-width panels.  Because of this, while you can specify any number of columns
     * with different percentages, the columnWidths must always add up to 1 (or 100%) when added together, otherwise your
     * layout may not render as expected.
     * {@img Ext.layout.container.Column/Ext.layout.container.Column1.png Ext.layout.container.Column container layout}
     * Example usage:</p>
     * <pre><code>
        // All columns are percentages -- they must add up to 1
        Ext.create('Ext.panel.Panel', {
            title: 'Column Layout - Percentage Only',
            width: 350,
            height: 250,
            layout:'column',
            items: [{
                title: 'Column 1',
                columnWidth: .25
            },{
                title: 'Column 2',
                columnWidth: .55
            },{
                title: 'Column 3',
                columnWidth: .20
            }],
            renderTo: Ext.getBody()
        });

    // {@img Ext.layout.container.Column/Ext.layout.container.Column2.png Ext.layout.container.Column container layout}
    // Mix of width and columnWidth -- all columnWidth values must add up
    // to 1. The first column will take up exactly 120px, and the last two
    // columns will fill the remaining container width.

        Ext.create('Ext.Panel', {
            title: 'Column Layout - Mixed',
            width: 350,
            height: 250,
            layout:'column',
            items: [{
                title: 'Column 1',
                width: 120
            },{
                title: 'Column 2',
                columnWidth: .7
            },{
                title: 'Column 3',
                columnWidth: .3
            }],
            renderTo: Ext.getBody()
        });
    </code></pre>
     */
    Ext.define('Ext.layout.container.Column', {

        extend: 'Ext.layout.container.Auto',
        alias: ['layout.column'],
        alternateClassName: 'Ext.layout.ColumnLayout',

        type: 'column',

        itemCls: Ext.baseCSSPrefix + 'column',

        targetCls: Ext.baseCSSPrefix + 'column-layout-ct',

        scrollOffset: 0,

        bindToOwnerCtComponent: false,

        getRenderTarget : function() {
            if (!this.innerCt) {

                // the innerCt prevents wrapping and shuffling while
                // the container is resizing
                this.innerCt = this.getTarget().createChild({
                    cls: Ext.baseCSSPrefix + 'column-inner'
                });

                // Column layout uses natural HTML flow to arrange the child items.
                // To ensure that all browsers (I'm looking at you IE!) add the bottom margin of the last child to the
                // containing element height, we create a zero-sized element with style clear:both to force a "new line"
                this.clearEl = this.innerCt.createChild({
                    cls: Ext.baseCSSPrefix + 'clear',
                    role: 'presentation'
                });
            }
            return this.innerCt;
        },

        // private
        onLayout : function() {
            var me = this,
                target = me.getTarget(),
                items = me.getLayoutItems(),
                len = items.length,
                item,
                i,
                parallelMargins = [],
                itemParallelMargins,
                size,
                availableWidth,
                columnWidth;

            size = me.getLayoutTargetSize();
            if (size.width < len * 10) { // Don't lay out in impossibly small target (probably display:none, or initial, unsized Container)
                return;
            }

            // On the first pass, for all except IE6-7, we lay out the items with no scrollbars visible using style overflow: hidden.
            // If, after the layout, it is detected that there is vertical overflow,
            // we will recurse back through here. Do not adjust overflow style at that time.
            if (me.adjustmentPass) {
                if (Ext.isIE6 || Ext.isIE7 || Ext.isIEQuirks) {
                    size.width = me.adjustedWidth;
                }
            } else {
                i = target.getStyle('overflow');
                if (i && i != 'hidden') {
                    me.autoScroll = true;
                    if (!(Ext.isIE6 || Ext.isIE7 || Ext.isIEQuirks)) {
                        target.setStyle('overflow', 'hidden');
                        size = me.getLayoutTargetSize();
                    }
                }
            }

            availableWidth = size.width - me.scrollOffset;
            me.innerCt.setWidth(availableWidth);

            // some columns can be percentages while others are fixed
            // so we need to make 2 passes
            for (i = 0; i < len; i++) {
                item = items[i];
                itemParallelMargins = parallelMargins[i] = item.getEl().getMargin('lr');
                if (!item.columnWidth) {
                    availableWidth -= (item.getWidth() + itemParallelMargins);
                }
            }

            availableWidth = availableWidth < 0 ? 0 : availableWidth;
            for (i = 0; i < len; i++) {
                item = items[i];
                if (item.columnWidth) {
                    columnWidth = Math.floor(item.columnWidth * availableWidth) - parallelMargins[i];
                    if (item.getWidth() != columnWidth) {
                        me.setItemSize(item, columnWidth, item.height);
                    }
                }
            }

            // After the first pass on an autoScroll layout, restore the overflow settings if it had been changed (only changed for non-IE6)
            if (!me.adjustmentPass && me.autoScroll) {

                // If there's a vertical overflow, relay with scrollbars
                target.setStyle('overflow', 'auto');
                me.adjustmentPass = (target.dom.scrollHeight > size.height);
                if (Ext.isIE6 || Ext.isIE7 || Ext.isIEQuirks) {
                    me.adjustedWidth = size.width - Ext.getScrollBarWidth();
                } else {
                    target.setStyle('overflow', 'auto');
                }

                // If the layout caused height overflow, recurse back and recalculate (with overflow setting restored on non-IE6)
                if (me.adjustmentPass) {
                    me.onLayout();
                }
            }
            delete me.adjustmentPass;
        }
    });