Fix T86867: Node Editor: Avoid deselect-all triggering on every box-

select

In 'Set/Replace' mode this is not a problem, but 'Extend' or 'Subtract'
modes were useless with the current behavior.
The problem here is that 'node.select' fires before 'node.select_box'
(which is fine) but deselects immediately on click.

This issue has come up before in other editors, see
{T70457}
{rB395dfff103e1}
{rBa8ea1ea1b7d5}

Now delay deselection in empty space to mouse release (same as done in
before mentioned report).

also related:
ref T57918
ref T63994

Maniphest Task: T86867

Differential Revision: https://developer.blender.org/D10801

1 files changed, 12 insertions, 4 deletions

diff --git a/source/blender/editors/space_node/node_select.c b/source/blender/editors/space_node/node_select.c
index 1da79671c8e..6548f6f5775 100644
--- a/source/blender/editors/space_node/node_select.c
+++ b/source/blender/editors/space_node/node_select.c
@@ -568,11 +568,19 @@ static int node_mouse_select(bContext *C,
       }
     }
     else if (deselect_all && node == NULL) {
-      /* Deselect in empty space. */
-      for (tnode = snode->edittree->nodes.first; tnode; tnode = tnode->next) {
-        nodeSetSelected(tnode, false);
+      /* Rather than deselecting others, users may want to drag to box-select (drag from empty
+       * space) or tweak-translate an already selected item. If these cases may apply, delay
+       * deselection. */
+      if (wait_to_deselect_others) {
+        ret_value = OPERATOR_RUNNING_MODAL;
+      }
+      else {
+        /* Deselect in empty space. */
+        for (tnode = snode->edittree->nodes.first; tnode; tnode = tnode->next) {
+          nodeSetSelected(tnode, false);
+        }
+        ret_value = OPERATOR_FINISHED;
       }
-      ret_value = OPERATOR_FINISHED;
     }
     else if (node != NULL) {
       /* When clicking on an already selected node, we want to wait to deselect