Fix T97386: Node socket labels swallow click/drag events

Regression caused by [0] which made `ui_but_is_interactive` consider
label buttons with tool-tips to be interactive. This prevented
the clicks to pass through to the nodes for selecting/dragging.

Resolve this by allowing buttons to be activated for the purpose
of showing tool-tips but otherwise considering them disabled
(as if the UI_BUT_DISABLED is set when handling events).

[0]: 484a9146479e05946d291e9886cdf3febca6d05d

Reviewed By: Severin

Ref D14932

3 files changed, 48 insertions, 13 deletions

diff --git a/source/blender/editors/interface/interface_handlers.c b/source/blender/editors/interface/interface_handlers.c
index 2c408619fe7..26b9b82d67f 100644
--- a/source/blender/editors/interface/interface_handlers.c
+++ b/source/blender/editors/interface/interface_handlers.c
@@ -384,6 +384,12 @@ typedef struct uiHandleButtonData {
 
   /* True when alt is held and the preference for displaying tooltips should be ignored. */
   bool tooltip_force;
+  /**
+   * Behave as if #UI_BUT_DISABLED is set (without drawing grayed out).
+   * Needed so non-interactive labels can be activated for the purpose of showing tool-tips,
+   * without them blocking interaction with nodes, see: T97386.
+   */
+  bool disable_force;
 
   /* auto open */
   bool used_mouse;
@@ -1669,7 +1675,7 @@ static void ui_drag_toggle_set(bContext *C, uiDragToggleHandle *drag_info, const
    */
   if (drag_info->is_xy_lock_init == false) {
     /* first store the buttons original coords */
-    uiBut *but = ui_but_find_mouse_over_ex(region, xy_input, true, NULL, NULL);
+    uiBut *but = ui_but_find_mouse_over_ex(region, xy_input, true, false, NULL, NULL);
 
     if (but) {
       if (but->flag & UI_BUT_DRAG_LOCK) {
@@ -1739,7 +1745,7 @@ static int ui_handler_region_drag_toggle(bContext *C, const wmEvent *event, void
   if (done) {
     wmWindow *win = CTX_wm_window(C);
     const ARegion *region = CTX_wm_region(C);
-    uiBut *but = ui_but_find_mouse_over_ex(region, drag_info->xy_init, true, NULL, NULL);
+    uiBut *but = ui_but_find_mouse_over_ex(region, drag_info->xy_init, true, false, NULL, NULL);
 
     if (but) {
       ui_apply_but_undo(but);
@@ -4324,7 +4330,7 @@ static uiBut *ui_but_list_row_text_activate(bContext *C,
                                             uiButtonActivateType activate_type)
 {
   ARegion *region = CTX_wm_region(C);
-  uiBut *labelbut = ui_but_find_mouse_over_ex(region, event->xy, true, NULL, NULL);
+  uiBut *labelbut = ui_but_find_mouse_over_ex(region, event->xy, true, false, NULL, NULL);
 
   if (labelbut && labelbut->type == UI_BTYPE_TEXT && !(labelbut->flag & UI_BUT_DISABLED)) {
     /* exit listrow */
@@ -7899,7 +7905,7 @@ static int ui_do_button(bContext *C, uiBlock *block, uiBut *but, const wmEvent *
   uiHandleButtonData *data = but->active;
   int retval = WM_UI_HANDLER_CONTINUE;
 
-  const bool is_disabled = but->flag & UI_BUT_DISABLED;
+  const bool is_disabled = but->flag & UI_BUT_DISABLED || data->disable_force;
 
   /* if but->pointype is set, but->poin should be too */
   BLI_assert(!but->pointype || but->poin);
@@ -8947,7 +8953,12 @@ static uiBut *ui_but_find_open_event(ARegion *region, const wmEvent *event)
 static int ui_handle_button_over(bContext *C, const wmEvent *event, ARegion *region)
 {
   if (event->type == MOUSEMOVE) {
-    uiBut *but = ui_but_find_mouse_over(region, event);
+    const bool labeledit = event->modifier & KM_CTRL;
+    /* Allow buttons to be activated to show the tool-tip,
+     * then force-disable them if they're not considered interactive
+     * so they don't swallow events but can still display tips. */
+    const bool for_tooltip = true;
+    uiBut *but = ui_but_find_mouse_over_ex(region, event->xy, labeledit, for_tooltip, NULL, NULL);
     if (but) {
       button_activate_init(C, region, but, BUTTON_ACTIVATE_OVER);
 
@@ -8956,6 +8967,10 @@ static int ui_handle_button_over(bContext *C, const wmEvent *event, ARegion *reg
          * preferences. */
         but->active->tooltip_force = true;
       }
+
+      if (but->active && !ui_but_is_interactive(but, labeledit)) {
+        but->active->disable_force = true;
+      }
     }
   }
   else if (event->type == EVT_BUT_OPEN) {
@@ -9435,7 +9450,7 @@ static bool ui_list_is_hovering_draggable_but(bContext *C,
   int mouse_xy[2];
   WM_event_drag_start_xy(event, mouse_xy);
 
-  const uiBut *hovered_but = ui_but_find_mouse_over_ex(region, mouse_xy, false, NULL, NULL);
+  const uiBut *hovered_but = ui_but_find_mouse_over_ex(region, mouse_xy, false, false, NULL, NULL);
 
   if (list->dyn_data->custom_drag_optype) {
     if (ui_but_context_poll_operator(C, list->dyn_data->custom_drag_optype, hovered_but)) {
diff --git a/source/blender/editors/interface/interface_intern.h b/source/blender/editors/interface/interface_intern.h
index c09ff68bbca..b1ca0fa4e92 100644
--- a/source/blender/editors/interface/interface_intern.h
+++ b/source/blender/editors/interface/interface_intern.h
@@ -1352,6 +1352,7 @@ bool ui_but_is_toggle(const uiBut *but) ATTR_WARN_UNUSED_RESULT;
  * \note ctrl is kind of a hack currently,
  * so that non-embossed UI_BTYPE_TEXT button behaves as a label when ctrl is not pressed.
  */
+bool ui_but_is_interactive_ex(const uiBut *but, const bool labeledit, const bool for_tooltip);
 bool ui_but_is_interactive(const uiBut *but, bool labeledit) ATTR_WARN_UNUSED_RESULT;
 bool ui_but_is_popover_once_compat(const uiBut *but) ATTR_WARN_UNUSED_RESULT;
 bool ui_but_has_array_value(const uiBut *but) ATTR_WARN_UNUSED_RESULT;
@@ -1388,6 +1389,7 @@ typedef bool (*uiButFindPollFn)(const uiBut *but, const void *customdata);
 uiBut *ui_but_find_mouse_over_ex(const struct ARegion *region,
                                  const int xy[2],
                                  bool labeledit,
+                                 bool for_tooltip,
                                  const uiButFindPollFn find_poll,
                                  const void *find_custom_data)
     ATTR_NONNULL(1, 2) ATTR_WARN_UNUSED_RESULT;
diff --git a/source/blender/editors/interface/interface_query.cc b/source/blender/editors/interface/interface_query.cc
index 337b2852d57..ea1fe3923e4 100644
--- a/source/blender/editors/interface/interface_query.cc
+++ b/source/blender/editors/interface/interface_query.cc
@@ -58,12 +58,23 @@ bool ui_but_is_toggle(const uiBut *but)
               UI_BTYPE_TREEROW);
 }
 
-bool ui_but_is_interactive(const uiBut *but, const bool labeledit)
+bool ui_but_is_interactive_ex(const uiBut *but, const bool labeledit, const bool for_tooltip)
 {
   /* NOTE: #UI_BTYPE_LABEL is included for highlights, this allows drags. */
-  if ((but->type == UI_BTYPE_LABEL) && but->dragpoin == nullptr && but->tip_func == nullptr) {
-    return false;
+  if (but->type == UI_BTYPE_LABEL) {
+    if (for_tooltip) {
+      /* It's important labels are considered interactive for the purpose of showing tooltip. */
+      if (but->dragpoin == nullptr && but->tip_func == nullptr) {
+        return false;
+      }
+    }
+    else {
+      if (but->dragpoin == nullptr) {
+        return false;
+      }
+    }
   }
+
   if (ELEM(but->type, UI_BTYPE_ROUNDBOX, UI_BTYPE_SEPR, UI_BTYPE_SEPR_LINE, UI_BTYPE_LISTBOX)) {
     return false;
   }
@@ -84,6 +95,11 @@ bool ui_but_is_interactive(const uiBut *but, const bool labeledit)
   return true;
 }
 
+bool ui_but_is_interactive(const uiBut *but, const bool labeledit)
+{
+  return ui_but_is_interactive_ex(but, labeledit, false);
+}
+
 bool UI_but_is_utf8(const uiBut *but)
 {
   if (but->rnaprop) {
@@ -266,6 +282,7 @@ static uiBut *ui_but_find(const ARegion *region,
 uiBut *ui_but_find_mouse_over_ex(const ARegion *region,
                                  const int xy[2],
                                  const bool labeledit,
+                                 const bool for_tooltip,
                                  const uiButFindPollFn find_poll,
                                  const void *find_custom_data)
 {
@@ -282,7 +299,7 @@ uiBut *ui_but_find_mouse_over_ex(const ARegion *region,
       if (find_poll && find_poll(but, find_custom_data) == false) {
         continue;
       }
-      if (ui_but_is_interactive(but, labeledit)) {
+      if (ui_but_is_interactive_ex(but, labeledit, for_tooltip)) {
         if (but->pie_dir != UI_RADIAL_NONE) {
           if (ui_but_isect_pie_seg(block, but)) {
             butover = but;
@@ -310,7 +327,8 @@ uiBut *ui_but_find_mouse_over_ex(const ARegion *region,
 
 uiBut *ui_but_find_mouse_over(const ARegion *region, const wmEvent *event)
 {
-  return ui_but_find_mouse_over_ex(region, event->xy, event->modifier & KM_CTRL, nullptr, nullptr);
+  return ui_but_find_mouse_over_ex(
+      region, event->xy, event->modifier & KM_CTRL, false, nullptr, nullptr);
 }
 
 uiBut *ui_but_find_rect_over(const struct ARegion *region, const rcti *rect_px)
@@ -414,7 +432,7 @@ static bool ui_but_is_listrow(const uiBut *but, const void *UNUSED(customdata))
 
 uiBut *ui_list_row_find_mouse_over(const ARegion *region, const int xy[2])
 {
-  return ui_but_find_mouse_over_ex(region, xy, false, ui_but_is_listrow, nullptr);
+  return ui_but_find_mouse_over_ex(region, xy, false, false, ui_but_is_listrow, nullptr);
 }
 
 struct ListRowFindIndexData {
@@ -446,7 +464,7 @@ static bool ui_but_is_treerow(const uiBut *but, const void *UNUSED(customdata))
 
 uiBut *ui_tree_row_find_mouse_over(const ARegion *region, const int xy[2])
 {
-  return ui_but_find_mouse_over_ex(region, xy, false, ui_but_is_treerow, nullptr);
+  return ui_but_find_mouse_over_ex(region, xy, false, false, ui_but_is_treerow, nullptr);
 }
 
 static bool ui_but_is_active_treerow(const uiBut *but, const void *customdata)