Let the user choose which settings persist

docs/USER_GUIDE.md

@@ -11,9 +11,9 @@ This guide is for new users. It explains what each control does and when to reac
 ### Screen layout
 
 *   **Left, the film strip**: your loaded frames as a contact sheet, plus import, sorting and triage tools.
-*   **Centre, the canvas**: the live preview. Most tools (crop, white-balance picker, heal brush, dodge/burn masks) are used by clicking directly on it. Scroll or pinch to zoom, drag to pan. A floating toolbar along the bottom holds Fit/1:1 zoom (**1:1** is one scan pixel per screen pixel, and lights up while you are at it; below **HQ** the preview is scaled up to reach it, which a **preview res · HQ off** pill on the canvas says), undo/redo, rotate/flip and more, moving overflow items into an **⋯** menu as the window narrows. **Edit Toolbar…** in that menu chooses which controls sit on the row and in what order (drag them into place); what does not fit collapses from the right, and the **⋯** menu keeps every action whatever the row shows. That menu also holds **Immersive Canvas** (the image fills the canvas and the toolbar overlaps it; turn it off to reserve space) **Show Slider Values** (every slider's value box stays open instead of appearing under the pointer) and **Reverse Scroll Zoom** (scroll up zooms out instead of in). Right-click the image for **Reset View** and **Sticky Zoom** (keeps the current zoom when you switch frames), plus the picker tools and copy/paste settings. With nothing loaded the canvas shows **Load some scans to get started**; click it for **Add files** or **Add folder**.
+*   **Centre, the canvas**: the live preview. Most tools (crop, white-balance picker, heal brush, dodge/burn masks) are used by clicking directly on it. Scroll or pinch to zoom, drag to pan. A floating toolbar along the bottom holds Fit/1:1 zoom (**1:1** is one scan pixel per screen pixel, and lights up while you are at it; below **HQ** the preview is scaled up to reach it, which a **preview res · HQ off** pill on the canvas says), undo/redo, rotate/flip and more, moving overflow items into an **⋯** menu as the window narrows. **Edit Toolbar…** in that menu chooses which controls sit on the row and in what order (drag them into place); what does not fit collapses from the right, and the **⋯** menu keeps every action whatever the row shows. That menu also holds **Immersive Canvas** (the image fills the canvas and the toolbar overlaps it; turn it off to reserve space) **Show Slider Values** (every slider's value box stays open instead of appearing under the pointer) and **Reverse Scroll Zoom** (scroll up zooms out instead of in). **Persistent Settings…** chooses which settings carry onto the next file you open. Right-click the image for **Reset View** and **Sticky Zoom** (keeps the current zoom when you switch frames), plus the picker tools and copy/paste settings. With nothing loaded the canvas shows **Load some scans to get started**; click it for **Add files** or **Add folder**.
 *   **Left, the film strip**: your loaded frames as a contact sheet, plus import, sorting, and triage tools.
-*   **Centre, the canvas**: the live preview of the current frame. Most tools (crop, white-balance picker, heal brush, dodge/burn masks) are used by clicking directly on it. Scroll/pinch to zoom and drag to pan; a floating toolbar along the bottom holds Fit/1:1 zoom (**1:1** is one scan pixel per screen pixel, and lights up while you are at it; below **HQ** the preview is scaled up to reach it, which a **preview res · HQ off** pill on the canvas says) plus undo/redo, rotate/flip and more, moving overflow items into an **⋯** menu when the window narrows. **Edit Toolbar…** in that menu chooses which controls sit on the row and in what order (drag them into place); what does not fit collapses from the right, and the **⋯** menu keeps every action whatever the row shows. That menu also has **Immersive Canvas** (image fills the canvas and the toolbar overlaps it; turn off to reserve space so it never occludes the image) **Show Slider Values** (keeps every slider's value box open instead of revealing it under the pointer; turn it on if you work by the numbers) and **Reverse Scroll Zoom** (scroll up zooms out instead of in). Right-click the image for **Reset View** and **Sticky Zoom** (keeps the current zoom level when you switch to another frame, instead of resetting to fit), alongside the picker tools, copy/paste settings, and **Unload** (removes the frame from the session; its saved edit is kept). With nothing loaded it shows **Load some scans to get started**; click it for **Add files** / **Add folder**.
+*   **Centre, the canvas**: the live preview of the current frame. Most tools (crop, white-balance picker, heal brush, dodge/burn masks) are used by clicking directly on it. Scroll/pinch to zoom and drag to pan; a floating toolbar along the bottom holds Fit/1:1 zoom (**1:1** is one scan pixel per screen pixel, and lights up while you are at it; below **HQ** the preview is scaled up to reach it, which a **preview res · HQ off** pill on the canvas says) plus undo/redo, rotate/flip and more, moving overflow items into an **⋯** menu when the window narrows. **Edit Toolbar…** in that menu chooses which controls sit on the row and in what order (drag them into place); what does not fit collapses from the right, and the **⋯** menu keeps every action whatever the row shows. That menu also has **Immersive Canvas** (image fills the canvas and the toolbar overlaps it; turn off to reserve space so it never occludes the image) **Show Slider Values** (keeps every slider's value box open instead of revealing it under the pointer; turn it on if you work by the numbers) and **Reverse Scroll Zoom** (scroll up zooms out instead of in). **Persistent Settings…** chooses which settings carry onto the next file you open. Right-click the image for **Reset View** and **Sticky Zoom** (keeps the current zoom level when you switch to another frame, instead of resetting to fit), alongside the picker tools, copy/paste settings, and **Unload** (removes the frame from the session; its saved edit is kept). With nothing loaded it shows **Load some scans to get started**; click it for **Add files** / **Add folder**.
 *   **Right, the controls**: a pinned **Analysis** readout at the top, and below it an icon tab bar. Each icon opens a *workflow page* holding one or more collapsible panels.
 
 ### Before / After
@@ -49,6 +49,14 @@ A small **dot** on a panel header, and on a tab icon, means you changed somethin
 
 Both side panels can be narrowed to give the canvas more room. As the controls panel shrinks, tab icons that no longer fit move into a **»** menu at the right of the tab bar. The tab you are on always stays visible.
 
+### What carries to the next frame
+
+Open a frame you have not edited and it does not start from bare defaults: the settings that belong to the *rig and the roll* rather than the picture come with it — film process, crop ratio, flips, calibration, paper stock, the Lab polish and your export preferences. The look itself (density, filtration, tone curve, toning, dodge and burn) starts clean on every frame.
+
+**Persistent Settings…** in the canvas **⋯** menu changes that list. Every setting the copy/paste picker knows is there, grouped by panel; tick one to make it carry, untick one to stop it. Tick the whole group from its header checkbox. Values shown are the ones from your last saved edit, so the list reads as what would actually carry.
+
+A frame you have already edited keeps its own look whatever you tick — only export and metadata settings reach it. **Reset Settings** on a frame ignores this list and returns it to bare defaults.
+
 ### Menu bar (macOS)
 
 On macOS NegPy has a menu bar. Almost nothing in it is new: apart from Report an Issue, every item runs something a button, a window control or a keyboard shortcut already runs.