Preserve sketch-pad background in typing mode

Sources/ZoomItMacCore/Overlay/ZoomCanvasView.swift

@@ -54,7 +54,10 @@ final class ZoomCanvasView: NSView {
             switch interactionMode {
             case .typing:
                 let wasDrawing = isDrawingMode
-                exitDrawingMode(restoreCursor: false)
+                exitDrawingMode(
+                    restoreCursor: false,
+                    clearBlankScreen: Self.clearsBlankScreenWhenLeavingDrawing(for: interactionMode)
+                )
                 // When coming from drawing, the pen dot is already tracked in
                 // pointerViewPoint; exitDrawingMode warps the system cursor, so
                 // don't re-read the mouse. Otherwise sync to the real cursor so
@@ -502,6 +505,10 @@ final class ZoomCanvasView: NSView {
         return .penColor
     }
 
+    static func clearsBlankScreenWhenLeavingDrawing(for mode: AppMode) -> Bool {
+        mode != .typing
+    }
+
     private func drawTypingCaret(in context: CGContext, source: CGRect) {
         guard let caret = annotationController.typingCaret() else { return }
         let color = annotationController.currentStyle.color.nsColor
@@ -559,12 +566,14 @@ final class ZoomCanvasView: NSView {
         updateLiveZoomInteractivity()
     }
 
-    private func exitDrawingMode(restoreCursor: Bool = true) {
+    private func exitDrawingMode(restoreCursor: Bool = true, clearBlankScreen: Bool = true) {
         guard isDrawingMode else { return }
         isDrawingMode = false
         isStroking = false
         activeStrokeTool = nil
-        blankScreen = nil
+        if clearBlankScreen {
+            blankScreen = nil
+        }
         stopDrawingRightClickMonitor()
         // Keep the zoom anchored where it was while drawing. The physical mouse
         // moved around the screen while drawing, so warp the (hidden) system
@@ -960,4 +969,4 @@ final class ZoomCanvasView: NSView {
         context.fillEllipse(in: rect)
         context.restoreGState()
     }
-}
+}

Sources/ZoomItMacCore/SelfTest/SelfTestRunner.swift

@@ -58,6 +58,7 @@ public enum SelfTestRunner {
         try testSettingsWindowStaysOnTop()
         try testZoomAndLiveZoomAreSeparateTabs()
         try testBlankScreenUsesControlKeys()
+        try testTypingPreservesBlankScreen()
         try testTypeTabFontSampleUsesSelectedFont()
         try testMenuBarIconIsPaddedTemplate()
         try testStandardIconIsRoundedSquareWithMargin()
@@ -702,6 +703,18 @@ public enum SelfTestRunner {
                    "Expected Ctrl+W/K outside drawing mode to fall back to the pen colour")
     }
 
+    private static func testTypingPreservesBlankScreen() throws {
+        try expect(!ZoomCanvasView.clearsBlankScreenWhenLeavingDrawing(for: .typing),
+                   "Expected leaving drawing for typing mode to preserve the sketch-pad background")
+
+        let modesThatShouldClear: [AppMode] = [.idle, .staticZoom, .drawOnly, .liveZoom, .captureSelection,
+                                              .panoramaCapture, .recording, .breakTimer]
+        for mode in modesThatShouldClear {
+            try expect(ZoomCanvasView.clearsBlankScreenWhenLeavingDrawing(for: mode),
+                       "Expected leaving drawing for \(mode) to clear the sketch-pad background")
+        }
+    }
+
     /// The Type tab's "Sample" preview must render in the selected typing font
     /// (it previously always used the system font, so font changes weren't
     /// visible). Also verify the preview size is clamped to a legible range.
@@ -1729,4 +1742,4 @@ private extension Array {
             Array(self[start..<Swift.min(start + size, count)])
         }
     }
-}
+}