From bc5dbd718e53e9cc5183d6037562c03f1d30c8b1 Mon Sep 17 00:00:00 2001
From: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>
Date: Tue, 20 Oct 2020 14:52:18 +0200
Subject: [PATCH] Fix: Context::wants_mouse_input() now returns false if a
 mouse drag started outside of Egui

---
 TODO.md             |  8 ++++++++
 egui/src/context.rs | 18 +++++++++++++++++-
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/TODO.md b/TODO.md
index 8d93f84e..557d5828 100644
--- a/TODO.md
+++ b/TODO.md
@@ -2,6 +2,14 @@
 
 TODO-list for the Egui project. If you looking for something to do, look here.
 
+## Top priority
+
+* Text input: text selection etc
+* Fix `is_mouse_over_area()` for menu bar:
+  * Probably a good time to create some sort of `ctx.top_panel()` allocation system and refactor paint layers
+
+## Other
+
 * Widgets
   * [ ] Tooltips:
     * [ ] Tooltip widget: Something that looks like this:  (?)  :that shows text on hover.
diff --git a/egui/src/context.rs b/egui/src/context.rs
index e98ea981..58847911 100644
--- a/egui/src/context.rs
+++ b/egui/src/context.rs
@@ -305,6 +305,8 @@ impl Context {
     pub fn is_mouse_over_area(&self) -> bool {
         if let Some(mouse_pos) = self.input.mouse.pos {
             if let Some(layer) = self.layer_at(mouse_pos) {
+                // TODO: this currently returns false for hovering the menu bar.
+                // We should probably move the menu bar to its own area to fix this.
                 layer.order != Order::Background
             } else {
                 false
@@ -319,10 +321,13 @@ impl Context {
     /// or the user is dragging an Egui widget.
     /// If false, the mouse is outside of any Egui area and so
     /// you may be interested in what it is doing (e.g. controlling your game).
+    /// Returns `false` if a drag starts outside of Egui and then moves over an Egui window.
     pub fn wants_mouse_input(&self) -> bool {
-        self.is_mouse_over_area() || self.is_using_mouse()
+        self.is_using_mouse() || (self.is_mouse_over_area() && !self.input().mouse.down)
     }
 
+    /// Is Egui currently using the mouse position (e.g. dragging a slider).
+    /// NOTE: this will return false if the mouse is just hovering over an Egui window.
     pub fn is_using_mouse(&self) -> bool {
         self.memory().interaction.is_using_mouse()
     }
@@ -528,6 +533,17 @@ impl Context {
     pub fn inspection_ui(&self, ui: &mut Ui) {
         use crate::containers::*;
 
+        ui.label(format!("Is using mouse: {}", self.is_using_mouse()))
+            .on_hover_text("Is Egui currently using the mouse actively (e.g. dragging a slider)?");
+        ui.label(format!("Wants mouse input: {}", self.wants_mouse_input()))
+            .on_hover_text("Is Egui currently interested in the location of the mouse (either because it is in use, or because it is hovering over a window).");
+        ui.label(format!(
+            "Wants keyboard input: {}",
+            self.wants_keyboard_input()
+        ))
+        .on_hover_text("Is Egui currently listening for text input");
+        ui.advance_cursor(16.0);
+
         CollapsingHeader::new("Input")
             .default_open(true)
             .show(ui, |ui| ui.input().clone().ui(ui));