Resolve "Simulate SFG in GUI"

Implemented the GUI handling of simulation of an SFG, also fixed some other stuff like new selection handling (any bugs are features), naming sfg, etc. Closes #88 (closed)

b_asic/GUI/drag_button.py

@@ -37,6 +37,10 @@ class DragButton(QPushButton):
         properties = QAction("Properties")
         menu.addAction(properties)
         properties.triggered.connect(self.show_properties_window)
+
+        delete = QAction("Delete")
+        menu.addAction(delete)
+        delete.triggered.connect(self.remove)
         menu.exec_(self.cursor().pos())
 
     def show_properties_window(self):
@@ -58,11 +62,12 @@ class DragButton(QPushButton):
         if event.buttons() == Qt.LeftButton and self._m_press:
             self._m_drag = True
             self.move(self.mapToParent(event.pos() - self._mouse_press_pos))
-            for button in self._window.pressed_operations:
-                if button is self:
-                    continue
+            if self in self._window.pressed_operations:
+                for button in self._window.pressed_operations:
+                    if button is self:
+                        continue
 
-                button.move(button.mapToParent(event.pos() - self._mouse_press_pos))
+                    button.move(button.mapToParent(event.pos() - self._mouse_press_pos))
 
         self._window.update()
         super(DragButton, self).mouseMoveEvent(event)
@@ -109,4 +114,10 @@ class DragButton(QPushButton):
             signal.update()
 
     def remove(self):
-        self.deleteLater()
\ No newline at end of file
+        self._window.scene.removeItem(self._window.operationDict[self])
+
+        if self in self._window.pressed_operations:
+            self._window.pressed_operations.remove(self)
+
+        if self in self._window.operationDict.keys():
+            del self._window.operationDict[self]
\ No newline at end of file