strange problem in using Gtk::IconView

非常奇怪的问题，在使用Gtk::IconView的时候遇到的。
假设model的数据重新刷新后，但和刷新前的数据相同，这时候IconView里的显示就会发生奇怪的现象，首先height边大，若再次刷新，则text会奇怪的显示（左对齐），而且text每行的长度很短，导致item的height被变相拉大。

Use Gtk::IconView to display some pdf’s thumbnail, and without any problem. But encounter a strange problem, the iconview item’s height will increase after a model’s update if the model’s content unchanged.
For e.g., I use a update() function to do the update thing:

refListModel->clear();
for(int i=0;iappend());
row[columns.id] = t[i].id;
row[columns.name] = t[i].name;
row[columns.click] = t[i].click;
row[columns.uri]=t[i].uri;
row[columns.pixbuf]=get_pixbuf(t[i].uri);
}
in this function, if the refListModel’s content same as before refListModel->clear() function, the iconview will get this problem.
So I don’t know, is this problem related with gtkmm or gtk+, and is this a bug or a feature?