Found an issue in GXT 3.0.2b with usage of HeaderGroupConfig (two rows). When I try to hide
a column on a GridView with forceFit set to false, the refresh() method resize all the next columns with the wrong size (all the size of the columns are shifted actually). I attached a patch fixing the issue:

Code:
### Eclipse Workspace Patch 1.0
#P GXT3.0
Index: com.sencha.gxt.ui/src/main/java/com/sencha/gxt/widget/core/client/grid/ColumnHeader.java
===================================================================
--- com.sencha.gxt.ui/src/main/java/com/sencha/gxt/widget/core/client/grid/ColumnHeader.java    (revision 2620)
+++ com.sencha.gxt.ui/src/main/java/com/sencha/gxt/widget/core/client/grid/ColumnHeader.java    (working copy)
@@ -538,6 +538,7 @@
         for (int k = mark; k < (mark + colspan); k++) {
           ColumnConfig<M, ?> c = cm.getColumn(k);
           if (c.isHidden()) {
+             mark++; // In the case of a hidden column, we need to increment  the marker for the next columns to retrieve the correct width
             continue;
           }
           w += cm.getColumnWidth(k);