因为家里电脑是Mac系统，所以就拿Mac系统来示范。

要注意的是gtk+2.0和3.0对字体的处理是有一些区别的：

1.后者使用的是pango的机制，我们这里以gtk+3.0为基础。

2.两者调用Font对话框的方法也不一样，前者用gtk_font_selection_dialog_new来建立对话框，还要设置button_ok按钮的回调函数，比较繁琐；后者用gtk_font_chooser_dialog_new建立对话框，可以直接取得字体名称，比较简洁。这里同样以3.0为基础。

下面上代码：

#include <gtk/gtk.h>
#include <string.h>

#define UI_PATH "./entry.ui"
#define MAIN_WINDOW "window"
#define ENTRY "entry"
#define CHK_EDITABLE "chk_editable"
#define CHK_VISIBLE "chk_visible"

static GtkWidget *w;
static GtkWidget *s_entry;
static GtkWidget *s_dialog_font = NULL;

void font_selection_ok(GtkWidget *button,gpointer user_data){
    GtkStyle *style;
    //GdkFont *font;

    //gchar *font_name = gtk_font_selection_dialog_get_font_name(GTK_IS_FONT_SELECTION_DIALOG(s_dialog_font));
    //printf("%s:font_name is %s\n",__func__,font_name);
    /*
    font = gtk_font_selection_dialog_get_font(GTK_IS_FONT_SELECTION_DIALOG(s_dialog_font));
    if(font){
        style = gtk_style_copy(gtk_widget_get_style(s_entry));
        gdk_font_unref(style->font);
        style->font = font;
        gdk_font_ref(style->font);
        gtk_widget_set_style(s_entry,style);
    }
    */
}

void font_changed(GtkWidget *self,gpointer user_data){
    s_dialog_font = gtk_font_chooser_dialog_new("Font Selection Dialog :)",GTK_WINDOW(w));
    gtk_window_set_transient_for(GTK_WINDOW(s_dialog_font),GTK_WINDOW(w));
    gtk_window_set_destroy_with_parent(GTK_WINDOW(s_dialog_font),TRUE);
    gtk_font_chooser_set_font(GTK_FONT_CHOOSER(s_dialog_font),NULL);
    if(gtk_dialog_run(GTK_DIALOG(s_dialog_font)) == GTK_RESPONSE_OK){
        gchar *font_name = gtk_font_chooser_get_font(GTK_FONT_CHOOSER(s_dialog_font));
        printf("%s:font_name is %s\n",__func__,font_name);
        PangoFontDescription *pfd = pango_font_description_from_string(font_name);
        //gtk_widget_modify_font(s_entry,pfd);
        gtk_widget_override_font(s_entry,pfd);
        pango_font_description_free(pfd);
    }
    gtk_widget_destroy(s_dialog_font);
/*
    if(!s_dialog_font){
        s_dialog_font = gtk_font_selection_dialog_new("Font Selection Dialog :)");
        g_return_if_fail(GTK_IS_FONT_SELECTION_DIALOG(s_dialog_font));
        //gtk_window_position(GTK_WINDOW(s_dialog_font),GTK_WIN_POS_MOUSE);
        gtk_window_set_position(GTK_WINDOW(s_dialog_font),GTK_WIN_POS_MOUSE);
        g_signal_connect(s_dialog_font,"destroy",
            G_CALLBACK(gtk_widget_destroyed),&s_dialog_font);
        g_signal_connect(gtk_font_selection_dialog_get_ok_button(
            GTK_IS_FONT_SELECTION_DIALOG(s_dialog_font)),
            "clicked",G_CALLBACK(font_selection_ok),NULL);
        g_signal_connect_swapped(gtk_font_selection_dialog_get_cancel_button(
            GTK_IS_FONT_SELECTION_DIALOG(s_dialog_font)),
            "clicked",G_CALLBACK(gtk_widget_destroy),s_dialog_font);
    }
    //if(!GTK_WIDGET_VISIBLE(s_dialog_font))
    if(!gtk_widget_get_visible(s_dialog_font))
        gtk_widget_show(s_dialog_font);
    else
        gtk_widget_destroy(s_dialog_font);
*/
}

void editable_toggled(GtkWidget *self,GtkEntry *entry){
    //gtk_entry_set_editable(entry,GTK_TOGGLE_BUTTON(self)->active);
    printf("%s:enter function\n",__func__);
    gtk_editable_set_editable((GtkEditable*)entry,gtk_toggle_button_get_active(
        GTK_TOGGLE_BUTTON(self)));
}

void visible_toggled(GtkWidget *self,GtkEntry *entry){
    //gtk_entry_set_visibility(entry,GTK_TOGGLE_BUTTON(self)->active);
    printf("%s:enter function\n",__func__);
    gtk_entry_set_visibility(entry,gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(self)));
}

void entry_changed(GtkWidget *self,gpointer user_data){
    gchar *text = (gchar*)gtk_entry_get_text(GTK_ENTRY(self));
    printf("%s:text is %s\n",__func__,text);
    text = g_ascii_strup(text,strlen(text));
    gtk_entry_set_text(GTK_ENTRY(self),text);
}

int main(int argc,char **argv){
    //GtkWidget *w;
    GError *error = NULL;
    gtk_init(&argc,&argv);
    GtkBuilder *builder = gtk_builder_new();
    if(!gtk_builder_add_from_file(builder,UI_PATH,&error)){
        g_critical("Couldn't load builder file: %s",error->message);
        g_error_free(error);
    }

    w = GTK_WIDGET(gtk_builder_get_object(builder,MAIN_WINDOW));
    if(!w){
        g_critical("Widget \"%s\" is missing in file %s",MAIN_WINDOW,UI_PATH);
    }
    gtk_window_set_title(GTK_WINDOW(w),"clist todo list");
    gtk_window_set_default_size(GTK_WINDOW(w),300,100);
    gtk_window_set_position(GTK_WINDOW(w),GTK_WIN_POS_CENTER_ALWAYS);
    gtk_container_set_border_width(GTK_CONTAINER(w),5);

    s_entry = GTK_WIDGET(gtk_builder_get_object(builder,ENTRY));

    gtk_builder_connect_signals(builder,NULL);
    g_object_unref(builder);

    gtk_widget_show_all(w);
    gtk_main();
    return 0;
}

entry.ui文件:

<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.18.3 -->
<interface>
  <requires lib="gtk+" version="3.12"/>
  <object class="GtkWindow" id="window">
    <property name="height_request">100</property>
    <property name="can_focus">False</property>
    <signal name="destroy" handler="gtk_main_quit" swapped="no"/>
    <child>
      <object class="GtkBox" id="box1">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <property name="orientation">vertical</property>
        <property name="spacing">10</property>
        <child>
          <object class="GtkGrid" id="grid1">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="column_spacing">5</property>
            <property name="column_homogeneous">True</property>
            <child>
              <object class="GtkLabel" id="label1">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="label" translatable="yes">大写化</property>
              </object>
              <packing>
                <property name="left_attach">0</property>
                <property name="top_attach">0</property>
              </packing>
            </child>
            <child>
              <object class="GtkEntry" id="entry">
                <property name="visible">True</property>
                <property name="can_focus">True</property>
                <property name="max_width_chars">50</property>
                <property name="shadow_type">etched-out</property>
                <property name="progress_pulse_step">0.089999999999999997</property>
                <property name="secondary_icon_stock">gtk-help</property>
                <property name="secondary_icon_tooltip_markup" translatable="yes">输入文本自动转换为大写</property>
                <signal name="changed" handler="entry_changed" swapped="no"/>
              </object>
              <packing>
                <property name="left_attach">1</property>
                <property name="top_attach">0</property>
                <property name="width">2</property>
              </packing>
            </child>
            <child>
              <object class="GtkButton" id="btn_font">
                <property name="label">gtk-select-font</property>
                <property name="visible">True</property>
                <property name="can_focus">True</property>
                <property name="receives_default">True</property>
                <property name="use_stock">True</property>
                <signal name="clicked" handler="font_changed" swapped="no"/>
              </object>
              <packing>
                <property name="left_attach">3</property>
                <property name="top_attach">0</property>
              </packing>
            </child>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">0</property>
          </packing>
        </child>
        <child>
          <object class="GtkBox" id="box2">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="homogeneous">True</property>
            <child>
              <object class="GtkAlignment" id="alignment1">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="xscale">0</property>
                <property name="yscale">0</property>
                <child>
                  <object class="GtkCheckButton" id="chk_editable">
                    <property name="label" translatable="yes">Editable</property>
                    <property name="visible">True</property>
                    <property name="can_focus">True</property>
                    <property name="receives_default">False</property>
                    <property name="xalign">0</property>
                    <property name="active">True</property>
                    <property name="draw_indicator">True</property>
                    <signal name="toggled" handler="editable_toggled" object="entry" swapped="no"/>
                  </object>
                </child>
              </object>
              <packing>
                <property name="expand">False</property>
                <property name="fill">True</property>
                <property name="position">0</property>
              </packing>
            </child>
            <child>
              <object class="GtkAlignment" id="alignment2">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="xscale">0</property>
                <property name="yscale">0</property>
                <child>
                  <object class="GtkCheckButton" id="chk_visible">
                    <property name="label" translatable="yes">Visible</property>
                    <property name="visible">True</property>
                    <property name="can_focus">True</property>
                    <property name="receives_default">False</property>
                    <property name="xalign">0</property>
                    <property name="active">True</property>
                    <property name="draw_indicator">True</property>
                    <signal name="toggled" handler="visible_toggled" object="entry" swapped="no"/>
                  </object>
                </child>
              </object>
              <packing>
                <property name="expand">False</property>
                <property name="fill">True</property>
                <property name="position">1</property>
              </packing>
            </child>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">1</property>
          </packing>
        </child>
        <child>
          <object class="GtkAlignment" id="alignment3">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <property name="xscale">0.5</property>
            <property name="yscale">0</property>
            <child>
              <object class="GtkButton" id="btn_ok">
                <property name="label" translatable="yes">O  K</property>
                <property name="visible">True</property>
                <property name="can_focus">True</property>
                <property name="receives_default">True</property>
                <signal name="clicked" handler="gtk_main_quit" swapped="yes"/>
              </object>
            </child>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">2</property>
          </packing>
        </child>
      </object>
    </child>
  </object>
</interface>

运行效果如下：