general misbehavior of screenshot "copy to clipboard" and "save" buttons when multiple are open

 * Cinnamon version: Cinnamon 5.4.12 (not daily)
 * Distribution - Mint 21
 * Graphics hardware *and* driver used: RTX3070 FE, nvidia-driver-515
 * 64 bit

Issue

When multiple captured-screenshot windows are open, pressing "Copy to Clipboard" on any of them results in the most recent screenshot being copied. Pressing "save" on any window closes all screenshots taken after.

Steps to reproduce

1. Capture >1 screenshots, leave the capture windows open
2. Press "copy to clipboard" on any window except the most recent
3. Paste somewhere, the most recent appears

alternately,

1. Capture >1 screenshots, leave the capture windows open
2. Press "save" on any window except the most recent.
3. See all subsequent screenshot windows disappear

Expected behaviour

"Copy to clipboard" should copy the screenshot shown in the window where the button was pressed, "save" should not affect other open screenshots

No file or test is named in the issue. Start by locating the screenshot capture window implementation and trace the handlers for “Copy to Clipboard” and “save” when multiple windows are open. Done means each button acts only on its own screenshot, with regression coverage for both reproduced cases.