**User:** Go to https://www.wavemetrics.com/forum/igor-pro-wish-list/simultaneously-set-opacity-multiple-traces-different-colors and read the request by the user and follow up comments. Suggest an outline of an implementation using Igor procedure code that could satisfy what the user asked for.

**GitHub Copilot:** 

Fetched https://www.wavemetrics.com/forum/igor-pro-wish-list/simultaneously-set-opacity-multiple-traces-different-colors

Based on the forum discussion, here's what was requested and an implementation outline:

## Summary of Request

**User gsb** wants to change opacity (alpha) of multiple selected traces while preserving their individual RGB colors. The built-in GUI sets all selected traces to the same color when changing opacity.

**Follow-up**: gsb mentioned wanting a listbox version to modify only a subset of traces, not all traces.

---

## Implementation Outline (Igor Procedure Code)

```igor
#pragma rtGlobals=3
#include <Graph Utility Procs>

// ============================================
// Panel-based Trace Opacity Editor
// ============================================

Menu "Graph"
    "Trace Opacity Editor...", ShowTraceOpacityPanel()
End

// Create the control panel
Function ShowTraceOpacityPanel()
    String gname = WinName(0, 1)
    if (strlen(gname) == 0)
        DoAlert 0, "No graph window found"
        return 0
    endif
    
    // Store current graph name
    String/G root:gCurrentGraph = gname
    
    // Build trace list wave for the ListBox
    BuildTraceListWave(gname)
    
    // Create panel
    DoWindow/K TraceOpacityPanel
    NewPanel/K=1/W=(100,100,450,500) as "Trace Opacity Editor"
    DoWindow/C TraceOpacityPanel
    
    // Graph selector popup
    PopupMenu graphPopup, pos={10,10}, size={200,20}
    PopupMenu graphPopup, value=WinList("*",";","WIN:1"), proc=GraphPopupProc
    
    // ListBox for trace selection (multi-select enabled)
    ListBox traceListBox, pos={10,40}, size={320,300}
    ListBox traceListBox, listWave=root:wTraceNames, selWave=root:wTraceSelection
    ListBox traceListBox, mode=4  // Multiple selection with checkboxes
    
    // Alpha slider
    TitleBox alphaLabel, pos={10,350}, title="Opacity (Alpha):"
    Slider alphaSlider, pos={10,370}, size={250,20}
    Slider alphaSlider, limits={0,65535,1}, value=65535, proc=AlphaSliderProc
    
    // Value display
    SetVariable alphaValue, pos={270,370}, size={70,20}, title=""
    SetVariable alphaValue, value=_NUM:65535, limits={0,65535,1}
    
    // Buttons
    Button applyBtn, pos={10,400}, size={100,25}, title="Apply", proc=ApplyAlphaProc
    Button selectAllBtn, pos={120,400}, size={80,25}, title="Select All", proc=SelectAllProc
    Button selectNoneBtn, pos={210,400}, size={80,25}, title="Select None", proc=SelectNoneProc
End

// Build waves for ListBox display
Function BuildTraceListWave(String gname)
    String traces = TraceNameList(gname, ";", 1)
    Variable ntraces = ItemsInList(traces)
    
    Make/O/T/N=(ntraces) root:wTraceNames
    Make/O/N=(ntraces) root:wTraceSelection = 0  // Selection state
    Make/O/N=(ntraces) root:wTraceAlpha       // Store current alpha values
    
    WAVE/T wTraceNames = root:wTraceNames
    WAVE wTraceAlpha = root:wTraceAlpha
    
    Variable i
    for (i = 0; i < ntraces; i++)
        String tname = StringFromList(i, traces)
        wTraceNames[i] = tname
        
        // Get current alpha value
        String info = TraceInfo(gname, tname, 0)
        String color = WMGetRECREATIONInfoByKey("rgb(x)", info)
        // Parse alpha if present (4th value), else default to 65535
        if (ItemsInList(color, ",") >= 4)
            wTraceAlpha[i] = str2num(StringFromList(3, color, ","))
        else
            wTraceAlpha[i] = 65535
        endif
    endfor
End

// Apply alpha to selected traces only
Function ApplyAlphaProc(ba) : ButtonControl
    STRUCT WMButtonAction &ba
    
    if (ba.eventCode != 2)  // Mouse up
        return 0
    endif
    
    SVAR gname = root:gCurrentGraph
    WAVE/T wTraceNames = root:wTraceNames
    WAVE wTraceSelection = root:wTraceSelection
    
    ControlInfo alphaSlider
    Variable alpha = V_Value
    
    SetSelectedTracesAlpha(gname, wTraceNames, wTraceSelection, alpha)
End

// Core function: Set alpha for selected traces while preserving RGB
Function SetSelectedTracesAlpha(String gname, WAVE/T traceNames, WAVE selection, Variable alpha)
    Variable i, ntraces = numpnts(traceNames)
    
    for (i = 0; i < ntraces; i++)
        if (selection[i] == 0)
            continue  // Skip unselected traces
        endif
        
        String tname = traceNames[i]
        String info = TraceInfo(gname, tname, 0)
        String color = WMGetRECREATIONInfoByKey("rgb(x)", info)
        
        // Parse existing RGB values
        String redstr = StringFromList(0, color, ",")
        Variable red = str2num(redstr[1,inf])  // Skip leading "("
        Variable green = str2num(StringFromList(1, color, ","))
        String bluestr = StringFromList(2, color, ",")
        Variable blue = str2num(ReplaceString(")", bluestr, ""))
        
        // Apply new alpha while preserving RGB
        ModifyGraph/W=$gname rgb($tname)=(red, green, blue, alpha)
    endfor
End

// Helper procs for selection buttons
Function SelectAllProc(ba) : ButtonControl
    STRUCT WMButtonAction &ba
    if (ba.eventCode == 2)
        WAVE wTraceSelection = root:wTraceSelection
        wTraceSelection = 1
    endif
End

Function SelectNoneProc(ba) : ButtonControl  
    STRUCT WMButtonAction &ba
    if (ba.eventCode == 2)
        WAVE wTraceSelection = root:wTraceSelection
        wTraceSelection = 0
    endif
End

// Graph popup handler
Function GraphPopupProc(pa) : PopupMenuControl
    STRUCT WMPopupAction &pa
    if (pa.eventCode == 2)
        String/G root:gCurrentGraph = pa.popStr
        BuildTraceListWave(pa.popStr)
    endif
End
```

---

## Key Features

| Feature | Description |
|---------|-------------|
| **ListBox selection** | Multi-select traces via checkboxes |
| **Preserve RGB** | Extracts existing RGB, applies new alpha only |
| **Graph selector** | Switch between open graph windows |
| **Slider control** | Real-time alpha value adjustment (0-65535) |
| **Select All/None** | Quick selection helpers |

## Extension Ideas

1. **Live preview** - Update alpha as slider moves via `AlphaSliderProc`
2. **Color preview column** - Show trace colors in the ListBox
3. **Undo support** - Store original alpha values for reverting
4. **Batch operations** - Apply to marker, bar stroke, error bar colors via additional keywords (`mrkStrokeRGB`, `barStrokeRGB`, etc.)

**User:** Create an .ipf file with the suggested implementation. Also write code I can execute within Igor Pro to create some example data and graph(s) that I can use to test the code you have written.

**GitHub Copilot:** Asked a question (File Path)

Ran terminal command: $env:USERPROFILE

Created [](file:///c%3A/Users/username/Documents/TraceOpacityEditor.ipf)

Created TraceOpacityEditor.ipf

## To Use

1. **Load the procedure** in Igor Pro:
   - File → Open File → Procedure... → select `TraceOpacityEditor.ipf`
   - Or copy to your `Igor Procedures` folder and restart Igor

2. **Create test data** by executing in the command line:
   ```
   CreateTestDataAndGraph()
   ```
   Or for overlapping traces (better for visualizing opacity):
   ```
   CreateOverlappingTestData()
   ```

3. **Open the editor**:
   - Graph menu → **Trace Opacity Editor...**
   - Or execute: `ShowTraceOpacityPanel()`

## Features

| Control | Function |
|---------|----------|
| **Graph popup** | Select which graph to edit |
| **ListBox** | Multi-select traces (Ctrl/Shift+click) |
| **Select All/None/Invert** | Quick selection helpers |
| **Alpha slider** | Set opacity 0 (invisible) to 65535 (opaque) |
| **Preview** | Temporarily apply without saving |
| **Apply** | Permanently set alpha for selected traces |
| **Undo** | Revert last Apply operation |

The two test functions create 6 or 10 traces in different colors so you can experiment with selecting subsets and changing their opacity independently.

Made changes.

**User:** line 495 compile error: 		String wname = "overlap" + num2str(i) "the name already exists as a variable"

**GitHub Copilot:** Replacing 4 lines with 4 lines in [](file:///c%3A/Users/username/Documents/TraceOpacityEditor.ipf)


```

```
Fixed. The variable `wname` was declared twice in the same function. Removed the duplicate `String` declaration in the second loop.

Made changes.

**User:** Here is a screenshot of the panel. Many of the controls at the bottom are overlapping and not visible.

**GitHub Copilot:** Read [](file:///c%3A/Users/username/Documents/TraceOpacityEditor.ipf#35-35), lines 35 to 85

Replacing 46 lines with 50 lines in [](file:///c%3A/Users/username/Documents/TraceOpacityEditor.ipf)


```

```
Fixed the layout issues:

1. **Made panel taller** (450px → 480px)
2. **Removed overlapping slider ticks** - replaced with static min/max labels
3. **Added help text** showing "(0=transparent, 65535=opaque)"
4. **Made alpha value field narrower** (45px) to fit
5. **Moved action buttons down** so they're fully visible

Close the panel and run `ShowTraceOpacityPanel()` again to see the updated layout.

Made changes.

**User:** Here is another screenshot. The bottom of the buttons is still cut off. So is the "gCurrentAlp..." text and anything else. It's possible that "gCurrentAlpha" is not the best string to use for a user-facing text label.

**GitHub Copilot:** Read [](file:///c%3A/Users/username/Documents/TraceOpacityEditor.ipf#37-37), lines 37 to 88

Replacing 52 lines with 53 lines in [](file:///c%3A/Users/username/Documents/TraceOpacityEditor.ipf)


```

```
Fixed:

1. **Panel height increased** (480px → 510px) 
2. **"gCurrentAlpha" replaced** with a proper "Value:" label above the input field
3. **Alpha group box made taller** to fit controls properly
4. **Action buttons moved down** so they're fully visible

Close and reopen the panel to see the updated layout.

Made changes.

**User:** Here is another screenshot. You've added "Value:" as a title box control but haven't changed the SetVariable position. There is no need for the TitleBox control. Instead you can change the title of the SetVariable control to something and Igor will display that. But the position of the control still needs to be fixed.

**GitHub Copilot:** Read [](file:///c%3A/Users/username/Documents/TraceOpacityEditor.ipf#63-63), lines 63 to 80

Replacing 18 lines with 17 lines in [](file:///c%3A/Users/username/Documents/TraceOpacityEditor.ipf)


```

```
Fixed:
- Removed the TitleBox
- Moved SetVariable to same row as slider (y=398)
- Set title to a single space to hide variable name
- Adjusted slider width and positions so everything fits on one line

Close and reopen the panel.

Made changes.

**User:** The preview button appears to apply the changes to the existing graph, which doesn't seem right.

**GitHub Copilot:** Read [](file:///c%3A/Users/username/Documents/TraceOpacityEditor.ipf#215-215), lines 215 to 270

Read [](file:///c%3A/Users/username/Documents/TraceOpacityEditor.ipf#270-270), lines 270 to 310

I see the issue. The "Preview" button does modify the graph - the only difference from "Apply" is that it doesn't update the internal saved state. This makes it confusing.

Let me redesign this with a clearer workflow: replace "Preview" with a "Live Preview" checkbox that updates the graph as you move the slider, and Undo will revert to whatever state was captured when you first opened the panel or last clicked Apply. 

Read [](file:///c%3A/Users/username/Documents/TraceOpacityEditor.ipf#75-75), lines 75 to 92

Replacing 36 lines with 48 lines in [](file:///c%3A/Users/username/Documents/TraceOpacityEditor.ipf)


```

```
Redesigned the workflow:

1. **Removed "Preview" button** - it was confusing since it modified the graph like Apply
2. **Added "Live Preview" checkbox** - when checked, the graph updates in real-time as you move the slider
3. **Undo** still reverts to the state before the last Apply

New behavior:
- **Live Preview off**: Adjust slider, then click "Apply to Selected" to see changes
- **Live Preview on**: Graph updates immediately as you drag the slider
- **Undo**: Reverts the last Apply operation

Reload the procedure and reopen the panel.

Made changes.