Fix image button padding on hover (#1595)

CHANGELOG.md

@@ -7,7 +7,7 @@ NOTE: [`epaint`](epaint/CHANGELOG.md), [`eframe`](eframe/CHANGELOG.md), [`egui-w
 ## Unreleased
 * Add `*_released` & `*_clicked` methods for `PointerState` ([#1582](https://github.com/emilk/egui/pull/1582)).
 * Optimize painting of filled circles (e.g. for scatter plots) by 10x or more ([#1616](https://github.com/emilk/egui/pull/1616)).
-
+* Fixed `ImageButton`'s changing background padding on hover ([#1595](https://github.com/emilk/egui/pull/1595)).
 
 ## 0.18.1 - 2022-05-01
 * Change `Shape::Callback` from `&dyn Any` to `&mut dyn Any` to support more backends.

egui/src/widgets/button.rs

@@ -489,18 +489,14 @@ impl Widget for ImageButton {
             let (expansion, rounding, fill, stroke) = if selected {
                 let selection = ui.visuals().selection;
                 (
-                    -padding,
+                    Vec2::ZERO,
                     Rounding::none(),
                     selection.bg_fill,
                     selection.stroke,
                 )
             } else if frame {
                 let visuals = ui.style().interact(&response);
-                let expansion = if response.hovered {
-                    Vec2::splat(visuals.expansion) - padding
-                } else {
-                    Vec2::splat(visuals.expansion)
-                };
+                let expansion = Vec2::splat(visuals.expansion);
                 (
                     expansion,
                     visuals.rounding,