Improve drag-code

crates/egui/src/input_state.rs

@@ -894,7 +894,8 @@ impl PointerState {
     }
 
     /// If the pointer button is down, will it register as a click when released?
-    #[inline(always)]
+    ///
+    /// See also [`Self::is_decidedly_dragging`].
     pub fn could_any_button_be_click(&self) -> bool {
         if !self.any_down() {
             return false;
@@ -913,6 +914,22 @@ impl PointerState {
         true
     }
 
+    /// Just because the mouse is down doesn't mean we are dragging.
+    /// We could be at the start of a click.
+    /// But if the mouse is down long enough, or has moved far enough,
+    /// then we consider it a drag.
+    ///
+    /// This function can return true on the same frame the drag is relased,
+    /// but NOT on the first frame it was started.
+    ///
+    /// See also [`Self::could_any_button_be_click`].
+    pub fn is_decidedly_dragging(&self) -> bool {
+        (self.any_down() || self.any_released())
+            && !self.any_pressed()
+            && !self.could_any_button_be_click()
+            && !self.any_click()
+    }
+
     /// Is the primary button currently down?
     #[inline(always)]
     pub fn primary_down(&self) -> bool {

crates/egui_extras/src/dock/branch/tabs.rs

@@ -3,8 +3,7 @@ use std::collections::HashMap;
 use egui::{vec2, Rect};
 
 use crate::dock::{
-    is_being_dragged, is_possible_drag, Behavior, DropContext, InsertionPoint, LayoutInsertion,
-    NodeId, Nodes,
+    is_being_dragged, Behavior, DropContext, InsertionPoint, LayoutInsertion, NodeId, Nodes,
 };
 
 #[derive(Clone, Debug, Default, serde::Serialize, serde::Deserialize)]
@@ -58,8 +57,7 @@ impl Tabs {
         let next_active = self.tab_bar_ui(behavior, ui, rect, nodes, drop_context, node_id);
 
         // When dragged, don't show it (it is "being held")
-        let is_active_being_dragged =
-            ui.memory(|mem| mem.is_being_dragged(self.active.id())) && is_possible_drag(ui.ctx());
+        let is_active_being_dragged = is_being_dragged(ui.ctx(), self.active);
         if !is_active_being_dragged {
             nodes.node_ui(behavior, drop_context, ui, self.active);
         }

crates/egui_extras/src/dock/mod.rs

@@ -165,11 +165,7 @@ enum SimplifyAction {
 }
 
 fn is_possible_drag(ctx: &egui::Context) -> bool {
-    ctx.input(|input| {
-        !input.pointer.any_pressed()
-            && !input.pointer.could_any_button_be_click()
-            && !input.pointer.any_click()
-    })
+    ctx.input(|input| input.pointer.is_decidedly_dragging())
 }
 
 fn is_being_dragged(ctx: &egui::Context, node_id: NodeId) -> bool {