Fixed the fonts size in HDPI mode.

qt-win.css

@@ -17,9 +17,3 @@ FileTableView QHeaderView::section:first {
 SyncErrorsTableView::item {
     padding-left: 2px;
 }
-
-AboutDialog QPushButton#mCheckUpdateBtn {
-    padding-left: 10px;
-    padding-right: 10px;
-}
-

src/utils/utils-win.cpp

@@ -220,7 +220,7 @@ bool fixQtHDPINonIntegerScaling()
         return false;
     }
     // Don't overwrite the user sepcified scaling factors
-    if (!qgetenv("QT_SCALE_FACTOR").isEmpty()) {
+    if (!qgetenv("QT_SCALE_FACTOR").isEmpty() || !qgetenv("QT_SCREEN_SCALE_FACTORS").isEmpty()) {
         return true;
     }
     // Don't overwrite the user sepcified multi-screen scaling factors
@@ -247,6 +247,7 @@ bool fixQtHDPINonIntegerScaling()
 
     // Turn off system scaling, otherwise we'll always see a 96 DPI virtual screen.
     if (!setProcessDPIAware()) {
+        return false;
     }
 
     QDpi dpi;
@@ -266,7 +267,12 @@ bool fixQtHDPINonIntegerScaling()
     //     192 DPI = 200% scaling
     double scaling_factor = ((double)(dpi.first)) / 96.0;
     QString factor = QString::number(scaling_factor);
-    g_setenv("QT_SCALE_FACTOR", factor.toUtf8().data(), 1);
+
+    // Use QT_SCREEN_SCALE_FACTORS instead of QT_SCALE_FACTOR. The latter would
+    // scale the font, which has already been scaled by the system.
+    //
+    // See also http://lists.qt-project.org/pipermail/interest/2015-October/019242.html
+    g_setenv("QT_SCREEN_SCALE_FACTORS", factor.toUtf8().data(), 1);
     // printf("set QT_SCALE_FACTOR to %s\n", factor.toUtf8().data());
     return true;
 }

ui/about-dialog.ui

@@ -122,20 +122,8 @@
        </property>
       </spacer>
      </item>
-     <item alignment="Qt::AlignHCenter">
+     <item>
       <widget class="QPushButton" name="mCheckUpdateBtn">
-       <property name="sizePolicy">
-        <sizepolicy hsizetype="Minimum" vsizetype="Fixed">
-         <horstretch>0</horstretch>
-         <verstretch>0</verstretch>
-        </sizepolicy>
-       </property>
-       <property name="minimumSize">
-        <size>
-         <width>92</width>
-         <height>23</height>
-        </size>
-       </property>
        <property name="text">
         <string>Check For Updates</string>
        </property>