value tab plots complex selection; graphwindows shows last path for export; filedialog uses call not init

src/gui_qt/io/exporters.py

@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+from pathlib import Path
+
 from numpy import c_
 
 from nmreval.io.graceeditor import GraceEditor
@@ -13,7 +15,7 @@ class GraceExporter:
         self.__agr = None
         self.__opts = kwargs
 
-    def export(self, outfile: str, mode: int | str = 'w'):
+    def export(self, outfile: str | Path, mode: int | str = 'w'):
         if mode == 'w':
             self.__agr = GraceEditor()
         else: