Google到了这个：http://ubuntuforums.org/showthread.php?t=1465712
简单地说就是:
1. 在控制台输入
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gedit ~/.gtkrc-2.0
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2. 复制下面的内容，保存，并重启Eclipse即可
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style "gtkcompact" {GtkButton::default_border={0,0,0,0}GtkButton::default_outside_border={0,0,0,0}GtkButtonBox::child_min_width=0GtkButtonBox::child_min_heigth=0GtkButtonBox::child_internal_pad_x=0GtkButtonBox::child_internal_pad_y=0GtkMenu::vertical-padding=1GtkMenuBar::internal_padding=0GtkMenuItem::horizontal_padding=4GtkToolbar::internal-padding=0GtkToolbar::space-size=0GtkOptionMenu::indicator_size=0GtkOptionMenu::indicator_spacing=0GtkPaned::handle_size=4GtkRange::trough_border=0GtkRange::stepper_spacing=0GtkScale::value_spacing=0GtkScrolledWindow::scrollbar_spacing=0GtkTreeView::vertical-separator=0GtkTreeView::horizontal-separator=0GtkTreeView::fixed-height-mode=TRUEGtkWidget::focus_padding=0}class "GtkWidget" style "gtkcompact"?