struct PatchEntry {

	byte flags; ///< Flags of the patch entry. @see PatchEntryFlags

	byte level; ///< Nesting level of this patch entry

	union {

		PatchEntrySetting entry; ///< Data fields if entry is a setting

		PatchEntrySubtree sub;   ///< Data fields if entry is a sub-page

	} d; ///< Data fields for each kind

	PatchEntry(const char *nm);

	PatchEntry(PatchPage *sub, StringID title);

	void Init(byte level, bool last_field);

	void SetButtons(byte new_val);

	uint Length() const;

	PatchEntry *FindEntry(uint row, uint *cur_row);

	uint Draw(GameSettings *patches_ptr, int base_x, int base_y, uint first_row, uint max_row, uint cur_row, uint parent_last);

private:

	void DrawPatch(GameSettings *patches_ptr, const SettingDesc *sd, int x, int y, int state);

};

/** Data structure describing one page of patches in the patch settings window. */

struct PatchPage {

	PatchEntry *entries; ///< Array of patch entries of the page.

	byte num;            ///< Number of entries on the page (statically filled).

	void Init(byte level = 0);

	uint Length() const;

	PatchEntry *FindEntry(uint row, uint *cur_row) const;

	uint Draw(GameSettings *patches_ptr, int base_x, int base_y, uint first_row, uint max_row, uint cur_row = 0, uint parent_last = 0) const;

};

/* == PatchEntry methods == */

/**

 * Constructor for a single setting in the 'advanced settings' window

	switch (this->flags & PEF_KIND_MASK) {

		case PEF_SETTING_KIND:

			this->d.entry.setting = GetPatchFromName(this->d.entry.name, &this->d.entry.index);

			assert(this->d.entry.setting != NULL);

			break;

		case PEF_SUBTREE_KIND:

			this->d.sub.page->Init(level + 1);

			break;

		default: NOT_REACHED();

	}

}

/**

 * Set the button-depressed flags (#PEF_LEFT_DEPRESSED and #PEF_RIGHT_DEPRESSED) to a specified value

 * @param new_val New value for the button flags

 * @see PatchEntryFlags

 */

void PatchEntry::SetButtons(byte new_val)

{

	assert((new_val & ~PEF_BUTTONS_MASK) == 0); // Should not touch any flags outside the buttons

	this->flags = (this->flags & ~PEF_BUTTONS_MASK) | new_val;

}

/** Return numbers of rows needed to display the entry */

/**

 * Initialization of an entire setting page

 * @param level Nesting level of this page (internal variable, do not provide a value for it when calling)

 */

void PatchPage::Init(byte level)

{

	for (uint field = 0; field < this->num; field++) {

		this->entries[field].Init(level, field + 1 == num);

	}

}

/** Return number of rows needed to display the whole page */

uint PatchPage::Length() const

{

	uint length = 0;

	for (uint field = 0; field < this->num; field++) {

		length += this->entries[field].Length();

	}

	return length;

}

/**

 * Find the patch entry at row number \a row_num

		 */

		assert(this->widget[PATCHSEL_OPTIONSPANEL].left + 5 == SETTINGTREE_LEFT_OFFSET);

		assert(this->widget[PATCHSEL_OPTIONSPANEL].top + 5 == SETTINGTREE_TOP_OFFSET);

		static bool first_time = true;

		patches_ptr = (_game_mode == GM_MENU) ? &_settings_newgame : &_settings_game;

		/* Build up the dynamic settings-array only once per OpenTTD session */

		if (first_time) {

			_patches_main_page.Init();

			first_time = false;

		}

		this->valuewindow_entry = NULL; // No patch entry for which a entry window is opened

		this->clicked_entry = NULL; // No numeric patch setting buttons are depressed

		this->vscroll.pos = 0;

		this->vscroll.cap = (this->widget[PATCHSEL_OPTIONSPANEL].bottom - this->widget[PATCHSEL_OPTIONSPANEL].top - 8) / SETTING_HEIGHT;

		SetVScrollCount(this, _patches_main_page.Length());

		this->resize.step_height = SETTING_HEIGHT;

		this->resize.height = this->height;

		this->resize.step_width = 1;

		this->resize.width = this->width;

const int PatchesSelectionWindow::SETTINGTREE_TOP_OFFSET = 19;

static const Widget _patches_selection_widgets[] = {

{   WWT_CLOSEBOX,   RESIZE_NONE,  COLOUR_MAUVE,     0,    10,     0,    13, STR_00C5,                        STR_018B_CLOSE_WINDOW},

{    WWT_CAPTION,  RESIZE_RIGHT,  COLOUR_MAUVE,    11,   411,     0,    13, STR_CONFIG_PATCHES_CAPTION,      STR_018C_WINDOW_TITLE_DRAG_THIS},

{      WWT_PANEL,     RESIZE_RB,  COLOUR_MAUVE,     0,   399,    14,   187, 0x0,                             STR_NULL}, // PATCHSEL_OPTIONSPANEL

{  WWT_SCROLLBAR,    RESIZE_LRB,  COLOUR_MAUVE,   400,   411,    14,   175, 0x0,                             STR_0190_SCROLL_BAR_SCROLLS_LIST}, // PATCHSEL_SCROLLBAR

{  WWT_RESIZEBOX,   RESIZE_LRTB,  COLOUR_MAUVE,   400,   411,   176,   187, 0x0,                             STR_RESIZE_BUTTON}, // PATCHSEL_RESIZE

{   WIDGETS_END},

};

static const WindowDesc _patches_selection_desc = {

	WC_GAME_OPTIONS, WC_NONE,

	WDF_STD_TOOLTIPS | WDF_STD_BTN | WDF_DEF_WIDGET | WDF_RESIZABLE,

	_patches_selection_widgets,

};

void ShowPatchesSelection()

{

	DeleteWindowById(WC_GAME_OPTIONS, 0);

	new PatchesSelectionWindow(&_patches_selection_desc);

}