feat: stabilize ui during search (closes #5431)

src/ui/main-window/TilesPanel.swift

@@ -5,6 +5,9 @@ class TilesPanel: NSPanel {
     static var maxPossibleThumbnailSize = NSSize.zero
     static var maxPossibleAppIconSize = NSSize.zero
     static var shared: TilesPanel!
+    private var frozenTopCenter: NSPoint?
+    private var highWaterWidth: CGFloat = 0
+    private var highWaterHeight: CGFloat = 0
 
     convenience init() {
         self.init(contentRect: .zero, styleMask: .nonactivatingPanel, backing: .buffered, defer: false)
@@ -40,12 +43,37 @@ class TilesPanel: NSPanel {
             guard App.appIsBeingUsed else { return }
             setContentSize(TilesView.contentView.frame.size)
             guard App.appIsBeingUsed else { return }
-            NSScreen.preferred.repositionPanel(self)
+            repositionOrFreeze()
         }
         // prevent further AppKit work
         TilesView.clearNeedsLayout()
     }
 
+    private func repositionOrFreeze() {
+        let size = frame.size
+        guard TilesView.isSearchModeOn else {
+            NSScreen.preferred.repositionPanel(self)
+            resetFrozenPosition()
+            return
+        }
+        if size.width > highWaterWidth || size.height > highWaterHeight {
+            NSScreen.preferred.repositionPanel(self)
+            highWaterWidth = size.width
+            highWaterHeight = size.height
+            frozenTopCenter = NSPoint(x: frame.midX, y: frame.maxY)
+        } else if let topCenter = frozenTopCenter {
+            let x = topCenter.x - size.width * 0.5
+            let y = topCenter.y - size.height
+            setFrameOrigin(NSPoint(x: x, y: y))
+        }
+    }
+
+    func resetFrozenPosition() {
+        frozenTopCenter = nil
+        highWaterWidth = 0
+        highWaterHeight = 0
+    }
+
     override func orderOut(_ sender: Any?) {
         TilesView.clearNeedsLayout()
         if Preferences.fadeOutAnimation {

src/ui/main-window/TilesView.swift

@@ -53,6 +53,7 @@ class TilesView {
     static func endSearchSession() {
         searchField.stringValue = ""
         Windows.updateSearchQuery("")
+        TilesPanel.shared.resetFrozenPosition()
         searchMode = .off
         updateSearchFieldEditability()
     }
@@ -69,6 +70,7 @@ class TilesView {
 
     static func disableSearchMode() {
         guard searchMode != .off else { return }
+        TilesPanel.shared.resetFrozenPosition()
         searchMode = .off
         updateSearchFieldEditability()
         searchField.stringValue = ""
@@ -496,8 +498,10 @@ class TilesView {
         scrollView.contentView.frame.size = scrollView.frame.size
         searchField.isHidden = searchMode == .off
         if searchMode != .off {
-            searchField.frame.size = NSSize(width: TilesView.thumbnailsWidth, height: searchBarHeight)
-            searchField.frame.origin = CGPoint(x: originX, y: frameHeight - Appearance.windowPadding - searchBarHeight)
+            let searchWidth = minSearchWidth
+            searchField.frame.size = NSSize(width: searchWidth, height: searchBarHeight)
+            let searchX = originX + (TilesView.thumbnailsWidth - searchWidth) * 0.5
+            searchField.frame.origin = CGPoint(x: searchX, y: frameHeight - Appearance.windowPadding - searchBarHeight)
         }
         if App.shared.userInterfaceLayoutDirection == .rightToLeft {
             let croppedWidth = max(0, TilesView.thumbnailsWidth - maxX)