Not fully tested, but I haven't found any issues, yet.

Say, you have a TreeGrid with folders and children (leaf) and you have added a CheckColumnConfig to get checkboxes in a column. You don't want to get checkboxes for the folders, only for the leaves:

Code:
Folder1
  Leaf1   X
Folder2
  Leaf2   X
  Leaf3   X
You can already disable checkboxes by overriding getCheckState and a -disable text:
Code:
CheckColumnConfig objCheckColumn = new CheckColumnConfig("flag", "Flag", 55) {
			protected String getCheckState(ModelData objModel, String strProperty, int intRowIndex, int intColIndex) {
				if (objModel instanceof FolderModel) {
					return "-disable";
				} else {
					return super.getCheckState(objModel, strProperty, intRowIndex, intColIndex);
				}
			}
		};
You can use this technology also, to hide the checkboxes completely:
Code:
CheckColumnConfig objCheckColumn = new CheckColumnConfig("flag", Flag", 55) {
			protected String getCheckState(ModelData objModel, String strProperty, int intRowIndex, int intColIndex) {
				// In the CheckColumnConfig.onRender method, the returned string is added to the 
				// term "x-grid3-check-col". See x-grid3-check-col-hidden definition in YOUR css file
				if (objModel instanceof FolderModel) {
					return "-hidden";
				} else {
					return super.getCheckState(objModel, strProperty, intRowIndex, intColIndex);
				}
			}
		};
Now add this CSS to your CSS file in the war folder:
Code:
.x-grid3-check-col-hidden {
	visibility:hidden;
}
Regards,

HerrB