modified the style of labels which are set not to have focus to make the selection visible.
place alert dialog center if it is out of range.
fixed wrong dialog window position.
place some dialogs at the center on parent window.
win32: make alert dialog in front on focus out.
modified alert dialogs.
added G_ALERTCANCEL to AlertValue, and return it if cancelled.
don't let some labels take focus.
modified AlertPanel's design to fit other GTK2 apps.
replaced intl.h with glib/gi18n.h.
alertpanel.c: use smaller size for title font.
alertpanel.c: generate title font from normal font.
src/alertpanel.c: use GTK stock icon instead of pixmap.
use GTK stock button for dialog button set.
alertpanel.c, about.c: made some label texts selectable.
Initial import of Sylpheed (GTK2 version).