feat(calendarium): add background opacity setting, always hide decorations

- Add bg-opacity scale setting (0=transparent, 1=solid black) to Appearance
- Always hide desklet frame and header via prevent-decorations metadata
- Remove hide-decorations toggle (no longer needed)
- Fix set_style ordering so background survives _updateDecoration() call
- Store desklet name in _deskletName for reuse

Author: KAMI911

calendarium@kami911/files/calendarium@kami911/desklet.js

@@ -118,8 +118,9 @@ CalendariumDesklet.prototype = {
         this._isDestroyed  = false;
         this._wikiRotateStep  = 0;   // advances each minute to rotate Wikipedia items
         this._wikiOnThisDayData = null;  // cached full onthisday response
+        this._deskletName  = metadata.name || "Calendarium";
 
-        this.setHeader(metadata.name || "Calendarium");
+        this.setHeader(this._deskletName);
         this._bindAllSettings(desklet_id);
         try {
             this._setupUI();
@@ -223,7 +224,7 @@ CalendariumDesklet.prototype = {
         // Appearance
         s.bindProperty(IN, "icon-size",        "icon_size",        cb);
         s.bindProperty(IN, "text-scale",       "text_scale",       cb);
-        s.bindProperty(IN, "hide-decorations", "hide_decorations", cb);
+        s.bindProperty(IN, "bg-opacity",       "bg_opacity",       cb);
     },
 
     /**
@@ -748,10 +749,12 @@ CalendariumDesklet.prototype = {
     },
 
     _applyAppearance: function() {
-        // Text scale: adjust base font-size so the layout naturally expands/shrinks
-        let s = this.text_scale || 1.0;
+        let s     = this.text_scale || 1.0;
         let basePx = Math.round(13 * s);
-        this._container.set_style("font-size: " + basePx + "px;");
+        let op    = Math.max(0, Math.min(1, this.bg_opacity || 0));
+        let containerStyle =
+            "font-size: " + basePx + "px;" +
+            "background-color: rgba(0, 0, 0, " + op.toFixed(2) + ");";
 
         // Icon / symbol size for moon and zodiac symbols
         let px = this._getIconPx();
@@ -765,10 +768,11 @@ CalendariumDesklet.prototype = {
             "font-size: " + px + "px; padding-right: 5px;"
         );
 
-        // Decorations
-        if (this.hide_decorations) {
-            this.setHeader(" ");
-        }
+        // Always hide frame and header — re-apply after _updateDecoration()
+        // which may reset container styles.
+        this.metadata["prevent-decorations"] = true;
+        this._updateDecoration();
+        this._container.set_style(containerStyle);
     },
 
     // ── Section updaters ──────────────────────────────────────────────────

calendarium@kami911/files/calendarium@kami911/settings-schema.json

@@ -127,7 +127,7 @@
         "section-appearance": {
             "type": "section",
             "title": "Appearance",
-            "keys": ["icon-size", "text-scale", "hide-decorations"]
+            "keys": ["icon-size", "text-scale", "bg-opacity"]
         }
     },
 
@@ -621,9 +621,13 @@
         "description": "Text scale factor",
         "tooltip": "Scale all text in the desklet up or down."
     },
-    "hide-decorations": {
-        "type": "checkbox",
-        "default": false,
-        "description": "Hide desklet decorations (border and header label)"
+    "bg-opacity": {
+        "type": "scale",
+        "default": 0.0,
+        "min": 0.0,
+        "max": 1.0,
+        "step": 0.05,
+        "description": "Background opacity",
+        "tooltip": "0 = fully transparent (wallpaper shows through), 1 = solid black background"
     }
 }