Some example uses of XC and XPC...

... Really needed only for "White" but harmless in the other uses.  Also more
i18n-hint comments.

There may be need to disambiguate other strings.

src/PluginManager.cpp

@@ -1897,10 +1897,13 @@ bool PluginManager::DropFile(const wxString &fileName)
 
             // Ask whether to enable the plug-ins
             if (auto nIds = ids.size()) {
-               auto message = XP(
+               auto message = XPC(
+               /* i18n-hint A plug-in is an optional added program for a sound
+                effect, or generator, or analyzer */
                   "Enable this plug-in?\n",
                   "Enable these plug-ins?\n",
-                  0
+                  0,
+                  "plug-ins"
                )( nIds );
                for (const auto &name : names)
                   message.Join( Verbatim( name ), wxT("\n") );

src/commands/ScreenshotCommand.cpp

@@ -94,7 +94,8 @@ kBackgroundStrings[ ScreenshotCommand::nBackgrounds ] =
 {
    // These are acceptable dual purpose internal/visible names
    { XO("Blue") },
-   { XO("White") },
+   /* i18n-hint:  This really means the color, not as in "white noise" */
+   { XC("White", "color") },
    { XO("None") },
 };
 

src/effects/Noise.cpp

@@ -41,9 +41,13 @@ enum kTypes
 static const EnumValueSymbol kTypeStrings[nTypes] =
 {
    // These are acceptable dual purpose internal/visible names
-   { XO("White") },
-   { XO("Pink") },
-   { XO("Brownian") }
+   /* i18n-hint: not a color, but "white noise" having a uniform spectrum  */
+   { XC("White", "noise") },
+   /* i18n-hint: not a color, but "pink noise" having a spectrum with more power
+    in low frequencies */
+   { XC("Pink", "noise") },
+   /* i18n-hint: a kind of noise spectrum also known as "red" or "brown" */
+   { XC("Brownian", "noise") }
 };
 
 // Define keys, defaults, minimums, and maximums for the effect parameters