Add a known crash-causing issue

README.md

@@ -126,6 +126,7 @@ cat file.ans
 
 ## Known Issues
 
+- Dragging from outside the canvas to inside with Free-Form Select crashes the program, and with Select makes a stupid selection (using the starting mouse position from the last time you clicked on the canvas).
 - The Text tool doesn't collapse a text selection when typing. Undo/Redo doesn't work with text. Ctrl+Z will delete the textbox.
 - Selection box border is inside instead of outside (and lacks dashes). For the text box, I hid the border because it was too visually confusing, but it should also have an outer border.
 - Pick Color can't be cancelled, since it samples the color continuously.

paint.py

@@ -2853,6 +2853,12 @@ class PaintApp(App[None]):
             # Done selecting text
             self.selecting_text = False
             return
+        # TODO: FIXME: dragging from outside the canvas shouldn't make a selection
+        # and for Free-Form Select it gets ValueError: min() arg is an empty sequence
+        # - self.mouse_at_start is never unset so it can't be used to check if the mouse is down
+        # - self.canvas.pointer_active is always False during ToolStop currently so I can't use that
+        # I could make it be set to False after ToolStop, but I could also
+        # just make ToolStop not fire if ToolStart didn't fire, right?
         if self.selected_tool in [Tool.select, Tool.free_form_select, Tool.text] and self.mouse_at_start:
             # Finish making a selection
             if self.selected_tool == Tool.free_form_select: