Add an SDF picker for selecting a stuff done flag and optionally giving it a name.

In effect, this is a combination of two of the previous pickers:
the location picker, and the editable string picker.

This required quite a significant rework of how the tilemap places its children.

Currently it's only used in special node editing.
I plan to add its use in many other places too though.

src/scenedit/scen.sdfpicker.hpp

@@ -0,0 +1,38 @@
+//
+//  scen.sdfpicker.hpp
+//  BoE Scenario Editor
+//
+//  Created by Celtic Minstrel on 2025-03-02.
+//
+
+#ifndef BoE_scen_sdfpicker_h
+#define BoE_scen_sdfpicker_h
+
+#include <string>
+#include "location.hpp"
+#include "dialogxml/dialogs/dialog.hpp"
+
+class cTilemap;
+
+class cStuffDonePicker {
+	cDialog dlog;
+	location initial_sdf, chosen_sdf, viewport;
+	cTilemap* grid;
+	cTilemap* row_labels;
+	cTilemap* col_labels;
+	int rows, cols;
+	bool skipNextFocus = true;
+	void clamp_sdf();
+	void fill_names();
+	void save_names();
+	void select_active();
+	bool handle_close(std::string item_hit);
+	bool handle_scroll(std::string item_hit);
+	bool handle_select(bool losing);
+	bool handle_focus(std::string item_hit, bool losing);
+public:
+	cStuffDonePicker(location sdf);
+	location run();
+};
+
+#endif