Layout improvements

New Functionality Requests
#1

Here are some improvements that can be implemented in dhtmlx layout.

  1. The user should be able to specify if the collapsed cell border to be 0px. (not displayed)
  2. In case the header in the cell is hidden the icon for collapsing/expanding should be rendered over the cells dividers. When the cell is collapsed and the user has specified the width of the collapsed cell to be 0px the expand icon should be rendered to te end of the cell.
  3. The user should be able to attach toolbar and/or tabbar in the header of the layout cell.
  4. The user should be able to specify if the collapse/expand icon is visible in the layout cell header.
  5. If the user specify width of 1px for cells devider the dragging should be still possible (similar to gantt).
  6. The user should be able to specify throught the init method the style of the cells’ borders as well as the header color and borders.