Improve track default height / header width.

Related to #629

src/kdenlivesettings.kcfg

@@ -239,7 +239,7 @@
   <group name="timeline">
     <entry name="headerwidth" type="Int">
       <label>Default width for timeline track headers.</label>
-      <default>140</default>
+      <default>0</default>
     </entry>
     <entry name="defaultkeyframeinterp" type="Int">
       <label>Default interpolation for keyframes.</label>

src/mainwindow.cpp

@@ -1759,12 +1759,14 @@ bool MainWindow::readOptions()
         KdenliveSettings::setDefaultprojectfolder(dir.absolutePath());
     }
     if (KdenliveSettings::trackheight() == 0) {
-        QFontMetrics metrics(font());
-        int trackHeight = 2.2 * metrics.height();
-        QStyle *style = qApp->style();
-        trackHeight += style->pixelMetric(QStyle::PM_ToolBarIconSize) + 2 * style->pixelMetric(QStyle::PM_ToolBarItemMargin) +
-                       style->pixelMetric(QStyle::PM_ToolBarItemSpacing) + 2;
-        KdenliveSettings::setTrackheight(trackHeight == 0 ? 50 : trackHeight);
+        QFont ft = QFontDatabase::systemFont(QFontDatabase::SmallestReadableFont);
+        int trackHeight = qMax(50, (int) (3.6 * QFontInfo(ft).pixelSize() + 6));
+        KdenliveSettings::setTrackheight(trackHeight);
+    }
+    if (KdenliveSettings::headerwidth() == 0) {
+        QFont ft = QFontDatabase::systemFont(QFontDatabase::SmallestReadableFont);
+        int trackWidth = qMax(50, 6 * (int)(1.8 * QFontInfo(ft).pixelSize() + 2));
+        KdenliveSettings::setHeaderwidth(trackWidth);
     }
     bool firstRun = false;
     KConfigGroup initialGroup(config, "version");