From 9cd72e9b4eb29f464d720bb4bab0badd6fdaa343 Mon Sep 17 00:00:00 2001
From: Ellpeck <me@ellpeck.de>
Date: Sun, 14 Nov 2021 19:50:24 +0100
Subject: [PATCH] Fixed panels that don't auto-hide their scroll bars ignoring
 their width for child padding

---
 CHANGELOG.md              |  1 +
 MLEM.Ui/Elements/Panel.cs | 12 ++++++------
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0611ecf..d391afe 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -35,6 +35,7 @@ Improvements
 Fixes
 - Fixed VerticalSpace height parameter being an integer
 - Fixed text not being pasted into a text field at all if it contains characters that don't match the input rule
+- Fixed panels that don't auto-hide their scroll bars ignoring their width for child padding
 
 ### MLEM.Data
 Additions
diff --git a/MLEM.Ui/Elements/Panel.cs b/MLEM.Ui/Elements/Panel.cs
index 12fa24f..3db62b1 100644
--- a/MLEM.Ui/Elements/Panel.cs
+++ b/MLEM.Ui/Elements/Panel.cs
@@ -76,12 +76,6 @@ namespace MLEM.Ui.Elements {
                     AutoHideWhenEmpty = autoHideScrollbar,
                     IsHidden = autoHideScrollbar
                 };
-                if (autoHideScrollbar) {
-                    this.ScrollBar.OnAutoHide += e => {
-                        this.ChildPadding += new Padding(0, this.ScrollerSize.Value.X + this.ScrollBarOffset, 0, 0) * (e.IsHidden ? -1 : 1);
-                        this.SetAreaDirty();
-                    };
-                }
 
                 // handle automatic element selection, the scroller needs to scroll to the right location
                 this.OnSelectedElementChanged += (element, otherElement) => {
@@ -235,7 +229,13 @@ namespace MLEM.Ui.Elements {
             // the max value of the scrollbar is the amount of non-scaled pixels taken up by overflowing components
             var scrollBarMax = (childrenHeight - this.ChildPaddedArea.Height) / this.Scale;
             if (!this.ScrollBar.MaxValue.Equals(scrollBarMax, Epsilon)) {
+                var wasZero = this.ScrollBar.MaxValue <= Epsilon;
                 this.ScrollBar.MaxValue = scrollBarMax;
+                if (this.ScrollBar.MaxValue <= Epsilon != wasZero) {
+                    // update child padding based on whether the scroll bar is visible
+                    this.ChildPadding += new Padding(0, this.ScrollerSize.Value.X + this.ScrollBarOffset, 0, 0) * (this.ScrollBar.IsHidden ? -1 : 1);
+                    this.SetAreaDirty();
+                }
                 this.relevantChildrenDirty = true;
             }