Prevent dragging from SceneTree buttons

(cherry picked from commit 45d0799b5b)

editor/scene_tree_editor.cpp

@@ -928,6 +928,10 @@ Variant SceneTreeEditor::get_drag_data_fw(const Point2 &p_point, Control *p_from
 	if (!can_rename)
 		return Variant(); //not editable tree
 
+	if (tree->get_button_id_at_position(p_point) != -1) {
+		return Variant(); //dragging from button
+	}
+
 	Vector<Node *> selected;
 	Vector<Ref<Texture> > icons;
 	TreeItem *next = tree->get_next_selected(NULL);

scene/gui/tree.cpp

@@ -3799,6 +3799,47 @@ TreeItem *Tree::get_item_at_position(const Point2 &p_pos) const {
 	return NULL;
 }
 
+int Tree::get_button_id_at_position(const Point2 &p_pos) const {
+	if (root) {
+		Point2 pos = p_pos;
+		pos -= cache.bg->get_offset();
+		pos.y -= _get_title_button_height();
+		if (pos.y < 0) {
+			return -1;
+		}
+
+		if (h_scroll->is_visible_in_tree()) {
+			pos.x += h_scroll->get_value();
+		}
+		if (v_scroll->is_visible_in_tree()) {
+			pos.y += v_scroll->get_value();
+		}
+
+		int col, h, section;
+		TreeItem *it = _find_item_at_pos(root, pos, col, h, section);
+
+		if (it) {
+			const TreeItem::Cell &c = it->cells[col];
+			int col_width = get_column_width(col);
+
+			for (int i = 0; i < col; i++) {
+				pos.x -= get_column_width(i);
+			}
+
+			for (int j = c.buttons.size() - 1; j >= 0; j--) {
+				Ref<Texture> b = c.buttons[j].texture;
+				Size2 size = b->get_size() + cache.button_pressed->get_minimum_size();
+				if (pos.x > col_width - size.width) {
+					return c.buttons[j].id;
+				}
+				col_width -= size.width;
+			}
+		}
+	}
+
+	return -1;
+}
+
 String Tree::get_tooltip(const Point2 &p_pos) const {
 
 	if (root) {

scene/gui/tree.h

@@ -535,6 +535,7 @@ public:
 	TreeItem *get_item_at_position(const Point2 &p_pos) const;
 	int get_column_at_position(const Point2 &p_pos) const;
 	int get_drop_section_at_position(const Point2 &p_pos) const;
+	int get_button_id_at_position(const Point2 &p_pos) const;
 
 	void clear();