windows_clipboard_sadness.diff

Description: Clipboard handling on Windows is a mess. No matter how you do it,
programs will handle the alpha channel incorrectly. After much back and forth,
Qt picked a combination that works for stuff like Office, but in turn doesn't
work for stuff like CSP and SAI. Obviously we care way more about the latter, so
we pick a different combination.

--- a/src/plugins/platforms/windows/qwindowsmime.cpp
+++ b/src/plugins/platforms/windows/qwindowsmime.cpp
@@ -1053,11 +1053,11 @@
 {
     QVector<FORMATETC> formatetcs;
     if (mimeData->hasImage() && mimeType == u"application/x-qt-image") {
-        //add DIBV5 if image has alpha channel. Do not add CF_PNG here as it will confuse MS Office (QTBUG47656).
         auto image = qvariant_cast<QImage>(mimeData->imageData());
         if (!image.isNull() && image.hasAlphaChannel())
             formatetcs += setCf(CF_DIBV5);
         formatetcs += setCf(CF_DIB);
+        formatetcs += setCf(CF_PNG); // QTBUG-86848, Paste into GIMP queries for PNG.
     }
     if (!formatetcs.isEmpty())
         qCDebug(lcQpaMime) << __FUNCTION__ << mimeType << formatetcs;
@@ -1086,9 +1086,12 @@
     const QImage image = qvariant_cast<QImage>(mimeData->imageData());
     if (image.isNull())
         return false;
+    // QTBUG-11463, deny CF_DIB support for images with alpha to prevent loss of
+    // transparency in conversion.
     // QTBUG-64322: Use PNG only for transparent images as otherwise MS PowerPoint
     // cannot handle it.
-    return cf == CF_DIBV5 || cf == CF_DIB
+    return cf == CF_DIBV5
+        || (cf == CF_DIB && !image.hasAlphaChannel())
         || (cf == int(CF_PNG) && image.hasAlphaChannel());
 }