feat: improve the 3 colored buttons when hovering (closes #516)

alt-tab-macos.xcodeproj/project.pbxproj

@@ -15,8 +15,12 @@
 		BF0C829583ED47E458528F3A /* accessibility@2x.png in Resources */ = {isa = PBXBuildFile; fileRef = BF0C889529FF19620EDAC295 /* accessibility@2x.png */; };
 		BF0C83E902F75A97E8FD374A /* menubar-2@2x.png in Resources */ = {isa = PBXBuildFile; fileRef = BF0C8D3333653ACAEF730DD8 /* menubar-2@2x.png */; };
 		BF0C8406805BDEC5B69E8803 /* screen-recording@2x.png in Resources */ = {isa = PBXBuildFile; fileRef = BF0C8E25373671B528AD448D /* screen-recording@2x.png */; };
+		BF0C8477850829E15FD4DD43 /* close@2x.png in Resources */ = {isa = PBXBuildFile; fileRef = BF0C8F9CE1699644A22EAF2C /* close@2x.png */; };
 		BF0C852D28E458CDD6FA3E44 /* app.icns in Resources */ = {isa = PBXBuildFile; fileRef = BF0C84E11784B3B0900D0963 /* app.icns */; };
+		BF0C89DF22C7B7D0C27DA2A4 /* WindowControlView.swift in Sources */ = {isa = PBXBuildFile; fileRef = BF0C884157B87BF0E17EF7F8 /* WindowControlView.swift */; };
 		BF0C8C9CA44285E493918A74 /* menubar-3@2x.png in Resources */ = {isa = PBXBuildFile; fileRef = BF0C8E54658B4DAEA0528200 /* menubar-3@2x.png */; };
+		BF0C8CB668FFABBCA23880B6 /* minimize@2x.png in Resources */ = {isa = PBXBuildFile; fileRef = BF0C817D9C335EE4A0536601 /* minimize@2x.png */; };
+		BF0C8F80281B50D57C95ECCF /* fullscreen@2x.png in Resources */ = {isa = PBXBuildFile; fileRef = BF0C83BD867F6A874F9953C9 /* fullscreen@2x.png */; };
 		BF0C8FA2D756D3258E3A16B6 /* Localizable.strings in Resources */ = {isa = PBXBuildFile; fileRef = BF0C81DF55C6B0A279CE0FE1 /* Localizable.strings */; };
 		D04BA004884A273D4D2D3EF1 /* HelperExtensions.swift in Sources */ = {isa = PBXBuildFile; fileRef = D04BAD91161791D42FEC4A60 /* HelperExtensions.swift */; };
 		D04BA0182F4734A5C8BB63DC /* Localizable.strings in Resources */ = {isa = PBXBuildFile; fileRef = D04BA5461DAEE9B5350C3020 /* Localizable.strings */; };
@@ -124,13 +128,17 @@
 		481FE54624D2D387001032F1 /* alt-tab-macos-Bridging-Header.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "alt-tab-macos-Bridging-Header.h"; sourceTree = "<group>"; };
 		59DD4BE63D42EEFF1182BA7F /* Pods-alt-tab-macos.release.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-alt-tab-macos.release.xcconfig"; path = "Target Support Files/Pods-alt-tab-macos/Pods-alt-tab-macos.release.xcconfig"; sourceTree = "<group>"; };
 		672F94799CC7C90282AEB3EA /* Pods-alt-tab-macos.debug.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-alt-tab-macos.debug.xcconfig"; path = "Target Support Files/Pods-alt-tab-macos/Pods-alt-tab-macos.debug.xcconfig"; sourceTree = "<group>"; };
+		BF0C817D9C335EE4A0536601 /* minimize@2x.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "minimize@2x.png"; sourceTree = "<group>"; };
 		BF0C81B8A30416D774B5B60E /* fullscreen.svg */ = {isa = PBXFileReference; lastKnownFileType = file.svg; path = fullscreen.svg; sourceTree = "<group>"; };
 		BF0C81C1B55A0519C3272B09 /* close.svg */ = {isa = PBXFileReference; lastKnownFileType = file.svg; path = close.svg; sourceTree = "<group>"; };
 		BF0C828AF7BCC4F47E70B28F /* menubar-2.svg */ = {isa = PBXFileReference; lastKnownFileType = file.svg; path = "menubar-2.svg"; sourceTree = "<group>"; };
 		BF0C833D471343CEA3DEFE56 /* icon_512x512@2x.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "icon_512x512@2x.png"; sourceTree = "<group>"; };
+		BF0C83BD867F6A874F9953C9 /* fullscreen@2x.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "fullscreen@2x.png"; sourceTree = "<group>"; };
 		BF0C843C2EDF4EF3A7A2C64A /* app.svg */ = {isa = PBXFileReference; lastKnownFileType = file.svg; path = app.svg; sourceTree = "<group>"; };
 		BF0C84E11784B3B0900D0963 /* app.icns */ = {isa = PBXFileReference; lastKnownFileType = image.icns; path = app.icns; sourceTree = "<group>"; };
+		BF0C86370093A080DD5974D8 /* convert_svg_to_png.sh */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.script.sh; path = convert_svg_to_png.sh; sourceTree = "<group>"; };
 		BF0C87B913292EE53EDE4220 /* menubar-1.svg */ = {isa = PBXFileReference; lastKnownFileType = file.svg; path = "menubar-1.svg"; sourceTree = "<group>"; };
+		BF0C884157B87BF0E17EF7F8 /* WindowControlView.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = WindowControlView.swift; sourceTree = "<group>"; };
 		BF0C889529FF19620EDAC295 /* accessibility@2x.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "accessibility@2x.png"; sourceTree = "<group>"; };
 		BF0C88BF67CF4D71002A60EB /* menubar-1@2x.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "menubar-1@2x.png"; sourceTree = "<group>"; };
 		BF0C88D6043B83B535BEAAA2 /* no */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.strings; name = no; path = Localizable.strings; sourceTree = "<group>"; };
@@ -140,6 +148,7 @@
 		BF0C8E54658B4DAEA0528200 /* menubar-3@2x.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "menubar-3@2x.png"; sourceTree = "<group>"; };
 		BF0C8F0D1F5E9980C2E1A073 /* no */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.strings; name = no; path = InfoPlist.strings; sourceTree = "<group>"; };
 		BF0C8F88F4326C82F16FD738 /* minimize.svg */ = {isa = PBXFileReference; lastKnownFileType = file.svg; path = minimize.svg; sourceTree = "<group>"; };
+		BF0C8F9CE1699644A22EAF2C /* close@2x.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "close@2x.png"; sourceTree = "<group>"; };
 		C0712B3BEA2B3780398C0999 /* Pods_alt_tab_macos.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = Pods_alt_tab_macos.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		D04BA015A45DE7AFDC9794FE /* Window.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Window.swift; sourceTree = "<group>"; };
 		D04BA03200F5A8FC0CD03607 /* CGWindowID.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = CGWindowID.swift; sourceTree = "<group>"; };
@@ -162,7 +171,7 @@
 		D04BA123744B0C27E9F54B05 /* codesign_sparkle_embedded_apps.sh */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.script.sh; path = codesign_sparkle_embedded_apps.sh; sourceTree = "<group>"; };
 		D04BA18724DC58FA95DB33DB /* Podfile.lock */ = {isa = PBXFileReference; lastKnownFileType = file.lock; path = Podfile.lock; sourceTree = "<group>"; };
 		D04BA18B55AA6C9EE41985D0 /* Contributing.md */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = net.daringfireball.markdown; path = Contributing.md; sourceTree = "<group>"; };
-		D04BA19E22F2B73DB785E5DB /* subset_fonticon.sh */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.script.sh; path = subset_fonticon.sh; sourceTree = "<group>"; };
+		D04BA19E22F2B73DB785E5DB /* subset_font.sh */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.script.sh; path = subset_font.sh; sourceTree = "<group>"; };
 		D04BA1B438BF3E65044D1138 /* ControlsTab.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ControlsTab.swift; sourceTree = "<group>"; };
 		D04BA1D80F4EEF2A91BAD29C /* release.config.js */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.javascript; path = release.config.js; sourceTree = "<group>"; };
 		D04BA1DF8CAB2FAB7FE9244B /* ThumbnailFontIconView.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ThumbnailFontIconView.swift; sourceTree = "<group>"; };
@@ -297,7 +306,7 @@
 		D04BACE22DC907F03D193075 /* GeneralTab.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = GeneralTab.swift; sourceTree = "<group>"; };
 		D04BACEE8D430B8CAAD8C4CD /* BoldLabel.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = BoldLabel.swift; sourceTree = "<group>"; };
 		D04BAD1297730B191E96E7FE /* ThumbnailTitleView.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ThumbnailTitleView.swift; sourceTree = "<group>"; };
-		D04BAD19B495AC18AC782A39 /* fonticon_to_image.sh */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.script.sh; path = fonticon_to_image.sh; sourceTree = "<group>"; };
+		D04BAD19B495AC18AC782A39 /* convert_font_to_png.sh */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.script.sh; path = convert_font_to_png.sh; sourceTree = "<group>"; };
 		D04BAD215A8F61F2D9952181 /* Introduction.md */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = net.daringfireball.markdown; path = Introduction.md; sourceTree = "<group>"; };
 		D04BAD241A6928F45355B315 /* es */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.strings; name = es; path = Localizable.strings; sourceTree = "<group>"; };
 		D04BAD2A5EFA477F1BC436B4 /* import_certificate_into_new_keychain.sh */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.script.sh; path = import_certificate_into_new_keychain.sh; sourceTree = "<group>"; };
@@ -418,6 +427,9 @@
 				BF0C81C1B55A0519C3272B09 /* close.svg */,
 				BF0C8F88F4326C82F16FD738 /* minimize.svg */,
 				BF0C81B8A30416D774B5B60E /* fullscreen.svg */,
+				BF0C8F9CE1699644A22EAF2C /* close@2x.png */,
+				BF0C817D9C335EE4A0536601 /* minimize@2x.png */,
+				BF0C83BD867F6A874F9953C9 /* fullscreen@2x.png */,
 			);
 			path = "window-controls";
 			sourceTree = "<group>";
@@ -699,6 +711,7 @@
 				D04BA1DF8CAB2FAB7FE9244B /* ThumbnailFontIconView.swift */,
 				D04BA258B56193958D60978A /* ThumbnailView.swift */,
 				D04BAA998119CAA8B70A2B67 /* ThumbnailsView.swift */,
+				BF0C884157B87BF0E17EF7F8 /* WindowControlView.swift */,
 			);
 			path = "main-window";
 			sourceTree = "<group>";
@@ -723,7 +736,7 @@
 				D04BAD6700415D6F7C8B2BEE /* travis.sh */,
 				D04BA81B25C166EFB3223639 /* extract_l10n_strings.sh */,
 				D04BA4FB0047656BEA21F1BE /* codesign */,
-				D04BA19E22F2B73DB785E5DB /* subset_fonticon.sh */,
+				D04BA19E22F2B73DB785E5DB /* subset_font.sh */,
 				D04BA48E6F24E0948C4CB4F7 /* import_l10n_strings_from_poeditor.sh */,
 				D04BAA5ECAE8BB8F8656DEDF /* update_contributors.sh */,
 				D04BAD65AA870A49D2F89DBC /* ensure_generated_files_are_up_to_date.sh */,
@@ -731,8 +744,9 @@
 				D04BAAE6E6823304D66B74F8 /* update_website.sh */,
 				D04BA7A758026814667273DC /* convert_iconset_to_icns.sh */,
 				D04BA6ED38651224DB117A5A /* upload_symbols_to_appcenter.sh */,
-				D04BAD19B495AC18AC782A39 /* fonticon_to_image.sh */,
+				D04BAD19B495AC18AC782A39 /* convert_font_to_png.sh */,
 				D04BA59FD487D0DEBBA66A94 /* createicns */,
+				BF0C86370093A080DD5974D8 /* convert_svg_to_png.sh */,
 			);
 			path = scripts;
 			sourceTree = "<group>";
@@ -1120,6 +1134,9 @@
 				BF0C8C9CA44285E493918A74 /* menubar-3@2x.png in Resources */,
 				BF0C829583ED47E458528F3A /* accessibility@2x.png in Resources */,
 				BF0C8406805BDEC5B69E8803 /* screen-recording@2x.png in Resources */,
+				BF0C8477850829E15FD4DD43 /* close@2x.png in Resources */,
+				BF0C8CB668FFABBCA23880B6 /* minimize@2x.png in Resources */,
+				BF0C8F80281B50D57C95ECCF /* fullscreen@2x.png in Resources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -1252,6 +1269,7 @@
 				D04BADA3F2DAB820D6FC6E75 /* AppCenterApplication.m in Sources */,
 				D04BAA16F21AC41A23DDA63D /* ControlsTab.swift in Sources */,
 				D04BADE4DDF7597749FB13BD /* PreferencesWindow.swift in Sources */,
+				BF0C89DF22C7B7D0C27DA2A4 /* WindowControlView.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

scripts/convert_svg_to_png.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+
+set -exu
+
+# needed because of macOS SIP (see https://stackoverflow.com/a/35570229)
+export DYLD_LIBRARY_PATH="$MAGICK_HOME/lib"
+
+currentDir="$(pwd)"
+size=16
+
+function convert() {
+  #  magick convert \
+  #    -background none \
+  #    -density 144 \
+  #    -resize 24x24 \
+  #    "resources/icons/window-controls/$1.svg" \
+  #    "resources/icons/window-controls/$1-magik.png"
+  /Applications/Inkscape.app/Contents/Resources/bin/inkscape \
+    -z \
+    -w "$((size * 2))" -h "$((size * 2))" \
+    "$currentDir/resources/icons/window-controls/$1.svg" \
+    -e "$currentDir/resources/icons/window-controls/$1@2x.png"
+}
+
+convert "close"
+convert "fullscreen"
+convert "minimize"

scripts/subset_font.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+
+set -exu
+
+"$(pipenv --venv)"/bin/pyftsubset resources/SF-Pro-Text-Regular-Full.otf \
+  --output-file=resources/SF-Pro-Text-Regular.otf \
+  --text="􀀁􀁎􀁌􀕧􀀸􀀺􀀼􀀾􀁀􀁂􀁄􀑱􀁆􀁈􀁊􀑳􀓵􀓶􀓷􀓸􀓹􀓺􀓻􀓼􀓽􀓾􀓿􀔀􀔁􀔂􀔃􀔄􀔅􀔆􀔇􀔈􀔉􀕬􀀹􀀻􀀽􀀿􀁁􀘘􀁃􀁅􀑲􀁇􀁉􀁋􀑴􀔔􀔕􀔖􀔗􀔘􀔙􀔚􀔛􀔜􀔝􀔞􀔟􀔠􀔡􀔢􀔣􀔤􀔥􀔦􀔧􀔨􀕭"

scripts/subset_fonticon.sh

@@ -1,7 +0,0 @@
-#!/usr/bin/env bash
-
-set -exu
-
-"$(pipenv --venv)"/bin/pyftsubset resources/SF-Pro-Text-Regular-Full.otf \
-  --output-file=resources/SF-Pro-Text-Regular.otf \
-  --text="􀀁􀁑􀁏􀁍􀁎􀁌􀕧􀕬􀀸􀀺􀀼􀀾􀁀􀁂􀁄􀑱􀁆􀁈􀁊􀑳􀓵􀓶􀓷􀓸􀓹􀓺􀓻􀓼􀓽􀓾􀓿􀔀􀔁􀔂􀔃􀔄􀔅􀔆􀔇􀔈􀔉􀀹􀀻􀀽􀀿􀁁􀘘􀁃􀁅􀑲􀁇􀁉􀁋􀑴􀔔􀔕􀔖􀔗􀔘􀔙􀔚􀔛􀔜􀔝􀔞􀔟􀔠􀔡􀔢􀔣􀔤􀔥􀔦􀔧􀔨􀕭"

src/api-wrappers/HelperExtensions.swift

@@ -158,4 +158,17 @@ extension NSImage {
         img.unlockFocus()
         return img
     }
+
+    func tinted(_ tint: NSColor) -> NSImage {
+        let dimmed = copy() as! NSImage
+        let scaling = Screen.withMouse()?.backingScaleFactor ?? 1
+        let scaledSize = NSSize(width: (size.width * scaling).rounded(), height: (size.height * scaling).rounded())
+        dimmed.size = scaledSize
+        dimmed.lockFocus()
+        tint.set()
+        let imageRect = NSRect(origin: .zero, size: scaledSize)
+        imageRect.fill(using: .sourceAtop)
+        dimmed.unlockFocus()
+        return dimmed
+    }
 }

src/logic/Screen.swift

@@ -14,7 +14,7 @@ class Screen {
         }
     }
 
-    private static func withMouse() -> NSScreen? {
+    static func withMouse() -> NSScreen? {
         return NSScreen.screens.first { NSMouseInRect(NSEvent.mouseLocation, $0.frame, false) }
     }
 

src/ui/main-window/ThumbnailFontIconView.swift

@@ -9,9 +9,6 @@ enum Symbols: String {
     case circledStar = "􀕬"
     case filledCircledStar = "􀕭"
     case filledCircled = "􀀁"
-    case filledCircledMultiplySign = "􀁑"
-    case filledCircledMinusSign = "􀁏"
-    case filledCircledPlusSign = "􀁍"
     case filledCircledNumber0 = "􀀹"
     case filledCircledNumber10 = "􀔔"
 }

src/ui/main-window/ThumbnailView.swift

@@ -10,9 +10,9 @@ class ThumbnailView: NSStackView {
     var hiddenIcon = ThumbnailFontIconView(.circledSlashSign)
     var spaceIcon = ThumbnailFontIconView(.circledNumber0)
     var dockLabelIcon = ThumbnailFilledFontIconView(ThumbnailFontIconView(.filledCircledNumber0, (Preferences.fontIconSize * 0.7).rounded(), NSColor(srgbRed: 1, green: 0.30, blue: 0.25, alpha: 1), nil), NSColor.white, true)
-    var closeIcon = ThumbnailFilledFontIconView(ThumbnailFontIconView(.filledCircledMultiplySign, Preferences.fontIconSize, NSColor(srgbRed: 1, green: 0.35, blue: 0.32, alpha: 1), nil), NSColor(srgbRed: 0.64, green: 0.03, blue: 0.02, alpha: 1))
+    var closeIcon = WindowControlView("close", 16)
-    var minimizeIcon = ThumbnailFilledFontIconView(ThumbnailFontIconView(.filledCircledMinusSign, Preferences.fontIconSize, NSColor(srgbRed: 0.91, green: 0.75, blue: 0.16, alpha: 1), nil), NSColor(srgbRed: 0.71, green: 0.55, blue: 0.09, alpha: 1))
+    var minimizeIcon = WindowControlView("minimize", 16)
-    var maximizeIcon = ThumbnailFilledFontIconView(ThumbnailFontIconView(.filledCircledPlusSign, Preferences.fontIconSize, NSColor(srgbRed: 0.32, green: 0.76, blue: 0.17, alpha: 1), nil), NSColor(srgbRed: 0.04, green: 0.39, blue: 0.02, alpha: 1))
+    var maximizeIcon = WindowControlView("fullscreen", 16)
     var hStackView: NSStackView!
     var mouseUpCallback: (() -> Void)!
     var mouseMovedCallback: (() -> Void)!
@@ -54,11 +54,11 @@ class ThumbnailView: NSStackView {
         thumbnail.addSubview(closeIcon, positioned: .above, relativeTo: nil)
         thumbnail.addSubview(minimizeIcon, positioned: .above, relativeTo: nil)
         thumbnail.addSubview(maximizeIcon, positioned: .above, relativeTo: nil)
-        let windowsControlSpacing = CGFloat(3)
         [closeIcon, minimizeIcon, maximizeIcon].forEach {
-            $0.topAnchor.constraint(equalTo: thumbnail.topAnchor, constant: 1).isActive = true
+            $0.topAnchor.constraint(equalTo: thumbnail.topAnchor, constant: 2).isActive = true
         }
-        closeIcon.leftAnchor.constraint(equalTo: thumbnail.leftAnchor).isActive = true
+        closeIcon.leftAnchor.constraint(equalTo: thumbnail.leftAnchor, constant: 3).isActive = true
+        let windowsControlSpacing = CGFloat(6)
         minimizeIcon.leftAnchor.constraint(equalTo: closeIcon.rightAnchor, constant: windowsControlSpacing).isActive = true
         maximizeIcon.leftAnchor.constraint(equalTo: minimizeIcon.rightAnchor, constant: windowsControlSpacing).isActive = true
         [closeIcon, minimizeIcon, maximizeIcon].forEach { $0.isHidden = true }
@@ -192,11 +192,25 @@ class ThumbnailView: NSStackView {
         if !isHighlighted {
             mouseMovedCallback()
         }
+        hoverWindowControls()
+    }
+
+    func hoverWindowControls() {
+        let controls = [closeIcon, minimizeIcon, maximizeIcon]
+        if let target = thumbnail.hitTest(convert(window!.convertPoint(fromScreen: NSEvent.mouseLocation), from: nil)),
+           target is NSImageView {
+            if let control = (controls.first { $0 == target }) {
+                control.hovered(true)
+                controls.filter { $0 != control }.forEach { $0.hovered(false) }
+            } else {
+                controls.forEach { $0.hovered(false) }
+            }
+        }
     }
 
     override func mouseUp(with event: NSEvent) {
         if event.clickCount >= 1 {
-            let target = thumbnail.hitTest(convert(event.locationInWindow, from: nil))?.superview
+            let target = thumbnail.hitTest(convert(event.locationInWindow, from: nil))
             if target == closeIcon {
                 window_!.close()
             } else if target == minimizeIcon {

src/ui/main-window/WindowControlView.swift

@@ -0,0 +1,24 @@
+import Cocoa
+
+class WindowControlView: NSImageView {
+    var originalImage: NSImage!
+    var hoveredImage: NSImage!
+    var size: NSSize!
+
+    convenience init(_ imageName: String, _ size_: Int) {
+        self.init()
+        translatesAutoresizingMaskIntoConstraints = false
+        size = NSSize(width: size_, height: size_)
+        let image = NSImage.initCopy(imageName)
+        image.size = size
+        originalImage = image
+        hoveredImage = image.tinted(.init(white: 0, alpha: 0.25))
+        hovered(false)
+    }
+
+    func hovered(_ isHovered: Bool) {
+        image = isHovered ? hoveredImage : originalImage
+        image!.size = size
+        frame.size = size
+    }
+}