Do not push to clipboard if the Terminal selection is empty

TermTk/TTkWidgets/TTkTerminal/terminal_screen.py

@@ -252,6 +252,8 @@ class _TTkTerminalScreen(_TTkTerminalScreen_CSI, _TTkTerminalScreen_C1):
         self._selectCursor.select(x,y,moveAnchor)
 
     def getSelected(self):
+        if not self._selectCursor.hasSelection():
+            return ""
         ret = []
 
         st = self._selectCursor.selectionStart()

TermTk/TTkWidgets/TTkTerminal/terminalview.py

@@ -988,8 +988,8 @@ class TTkTerminalView(TTkAbstractScrollView, _TTkTerminal_CSI_DEC):
 
     def mouseReleaseEvent(self, evt):
         self._selecting = False
-        selected = self._screen_current.getSelected()
-        self._clipboard.setText(selected)
+        if (selected := self._screen_current.getSelected()):
+            self._clipboard.setText(selected)
         return self._sendMouse(evt)
 
     def wheelEvent(self, evt):