Fix issue #280 - Close button doesn't appear in some windows

Thanks to @DocHoncho for the help.
See https://github.com/aseprite/aseprite/pull/6

src/ui/base.h

@@ -56,6 +56,7 @@ namespace ui {
 #define JI_DECORATIVE   0x0200 // To decorate windows.
 #define JI_INITIALIZED  0x0400 // The widget was already initialized by a theme.
 #define JI_DIRTY        0x0800 // The widget (or one child) is dirty (update_region != empty).
+#define JI_HASTEXT      0x1000 // The widget has text (at least setText() was called one time).
 
   class GuiSystem {
   public:

src/ui/widget.cpp

@@ -61,7 +61,6 @@ Widget::Widget(WidgetType type)
   this->m_theme = CurrentTheme::get();
 
   this->m_align = 0;
-  this->m_text = "";
   this->m_font = this->m_theme ? this->m_theme->default_font: NULL;
   this->m_bgColor = ui::ColorNone;
 
@@ -154,6 +153,7 @@ void Widget::setTextf(const char *format, ...)
 void Widget::setTextQuiet(const base::string& text)
 {
   m_text = text;
+  flags |= JI_HASTEXT;
 }
 
 FONT *Widget::getFont() const

src/ui/widget.h

@@ -105,7 +105,7 @@ namespace ui {
 
     // Text property.
 
-    bool hasText() const { return !m_text.empty(); }
+    bool hasText() const { return (flags & JI_HASTEXT) == JI_HASTEXT; }
 
     const base::string& getText() const { return m_text; }
     int getTextInt() const;