chore(tree)!: remove selected status from the treeWidgetItem (#584)

The selection state is now managed entirely by TTkTreeWidget instead of 
individual items. This improves performance and simplifies the API.

BREAKING CHANGE: The following APIs have been removed from TTkTreeWidgetItem:
- `isSelected()` method - use `TTkTreeWidget.selectedItems()` to check selection
- `setSelected(bool)` method - selection is now managed by TTkTreeWidget  
- `selected` parameter in constructor - no longer supported

Migration guide:
- Replace `item.isSelected()` with `item in treeWidget.selectedItems()`
- Remove calls to `item.setSelected(True/False)` - use tree widget selection methods
- Remove `selected=True` from TTkTreeWidgetItem() constructor calls

libs/pyTermTk/TermTk/TTkWidgets/TTkModelView/treewidget.py

@@ -566,11 +566,8 @@ class TTkTreeWidget(TTkAbstractScrollView):
                     self.itemExpanded.emit(item)
                 else:
                     self.itemCollapsed.emit(item)
-            for _s in self._selected:
-                _s.setSelected(False)
             self._selectedId = y
             self._selected = [item]
-            item.setSelected(True)
             col = -1
             for i, c in enumerate(self._columnsPos):
                 if x < c:
@@ -623,17 +620,13 @@ class TTkTreeWidget(TTkAbstractScrollView):
                 if self._selectionMode in (TTkK.SelectionMode.SingleSelection,TTkK.SelectionMode.MultiSelection):
                     _multiSelect = self._selectionMode == TTkK.SelectionMode.MultiSelection
                     if not ( bool(evt.mod & TTkK.ControlModifier) and _multiSelect ):
-                        for _s in self._selected:
-                            _s.setSelected(False)
                         self._selected.clear()
                     self._selectedId = y
                     # Unselect Items if already selected in multiselect mode
                     if item in self._selected and _multiSelect:
                         self._selected.remove(item)
-                        item.setSelected(False)
                     else:
                         self._selected.append(item)
-                        item.setSelected(True)
             col = -1
             for i, c in enumerate(self._columnsPos):
                 if x < c:
@@ -768,6 +761,6 @@ class TTkTreeWidget(TTkAbstractScrollView):
                     _text=_icon+_data[_yi]
                 else: # Other columns
                     _text=_data[_yi]
-                if _i.isSelected():
+                if _i in self._selected:
                     _text = (_text + ' '*_width).completeColor(selectedColor)
                 canvas.drawTTkString(text=_text,pos=(_lx-x,_y+1),width=_width)

libs/pyTermTk/TermTk/TTkWidgets/TTkModelView/treewidgetitem.py

@@ -251,7 +251,7 @@ class TTkTreeWidgetItem(TTkAbstractItemModel):
 
     __slots__ = (
         '_parent', '_data', '_widgets', '_height', '_alignment',
-        '_children', '_expanded', '_selected', '_hidden',
+        '_children', '_expanded', '_hidden',
         '_childIndicatorPolicy', '_icon', '_defaultIcon',
         '_sortColumn', '_sortOrder', '_hasWidgets',
         '_buffer', '_level',
@@ -271,7 +271,6 @@ class TTkTreeWidgetItem(TTkAbstractItemModel):
     def __init__(self, *args,
                  parent:Optional[TTkTreeWidgetItem]=None,
                  expanded:bool=False,
-                 selected:bool=False,
                  hidden:bool=False,
                  icon:TTkStringType='',
                  childIndicatorPolicy:TTkK.ChildIndicatorPolicy =TTkK.ChildIndicatorPolicy.DontShowIndicatorWhenChildless,
@@ -291,7 +290,6 @@ class TTkTreeWidgetItem(TTkAbstractItemModel):
         self._childIndicatorPolicy = childIndicatorPolicy
         self._defaultIcon = True
         self._expanded = expanded
-        self._selected = selected
         self._hidden = hidden
         self._sortColumn = -1
         self._sortOrder = TTkK.AscendingOrder
@@ -535,9 +533,6 @@ class TTkTreeWidgetItem(TTkAbstractItemModel):
     def emitDataChanged(self) -> None:
         self.dataChanged.emit()
 
-    # def setDisabled(disabled):
-    #    pass
-
     def setExpanded(self, expand:bool) -> None:
         if self._expanded != expand and self._children:
             if expand:
@@ -548,18 +543,9 @@ class TTkTreeWidgetItem(TTkAbstractItemModel):
         self._setDefaultIcon()
         self.dataChanged.emit()
 
-    def setSelected(self, select:bool) -> None:
-        self._selected = select
-
-    # def isDisabled():
-    #     pass
-
     def isExpanded(self) -> bool:
         return self._expanded
 
-    def isSelected(self) -> bool:
-        return self._selected
-
     def size(self) -> int:
         if self._hidden:
             return 0