The problem is caused by the Re-grid tab Columns value being set based on the assumption that the "1 new plot per curve" setting is selected. Either this setting needs to be reset when the user changes the setting or this needs to be an automatic option which generates a reasonable default.

I've been meaning to report this bug as well.  It's annoying.  My preference would be to:

a) put a default value in the columns box (as is currently done)

b) if the user has modifies the number of columns, leave it unchanged from then on; otherwise

c) modify the value as appropriate whenever the user modifies the number of plots the wizard will have to create

We need to indicate a 'default' state in the UI...
-another check box?
-convince the spinbox to allow 'default' as the value less than 1?

Created attachment 20373 [details]
Proposed patch for 1.5

SVN commit 659719 by arwalker:

BUG:144090 Correctly handle width of initial plot under all circumstances

 M  +23 -44    datawizard.ui.h  


--- branches/work/kst/1.5/kst/src/libkstapp/datawizard.ui.h #659718:659719
@@ -69,6 +69,10 @@
     _remove->setPixmap(BarIcon("back"));
     _remove->setAccel(ALT+Key_R);
 
+    _plotColumns->setMinValue(0);
+    _plotColumns->setMaxValue(10);
+    _plotColumns->setSpecialValueText(i18n("default"));
+
     loadSettings();
 
     QToolTip::add(_up, i18n("Raise in plot order: Alt+Up"));
@@ -365,23 +369,11 @@
     }
 
     if (v) {
-	const KstViewObjectList& children(v->view()->children());
-	int cnt = 0;
-	for (KstViewObjectList::ConstIterator i = children.begin(); i != children.end(); ++i) {
-	    if ((*i)->followsFlow()) {
-		++cnt;
-	    }
-	}
-
 	if (v->view()->onGrid()) {
-	    _plotColumns->setValue(int(floor(sqrt(_vectorsToPlot->childCount() + cnt))));
 	    _reGrid->setChecked(true);
 	} else {
-	    _plotColumns->setValue(int(floor(sqrt(_vectorsToPlot->childCount() + cnt))));
 	    _reGrid->setChecked(false);
 	}
-    } else {
-	_plotColumns->setValue(int(floor(sqrt(_vectorsToPlot->childCount()))));
     }
 }
 
@@ -435,7 +427,6 @@
     if (_existingPlot->isEnabled() && _existingPlotName->listBox() && _existingPlotName->listBox()->findItem(psave)) {
 	_existingPlotName->setCurrentText(psave);
     }
-    updateColumns();
 }
 
 
@@ -682,7 +673,7 @@
     // create the necessary plots
     app->slotUpdateProgress(n_steps, prg, i18n("Creating plots..."));
     KstViewObjectList plots;
-    bool relayout = true;
+
     if (_onePlot->isChecked()) {
 	Kst2DPlotPtr p = kst_cast<Kst2DPlot>(w->view()->findChild(w->createObject<Kst2DPlot>(KST::suggestPlotName(), false)));
 	plots.append(p.data());
@@ -720,13 +711,11 @@
     } else if (_existingPlot->isChecked()) {
 	Kst2DPlotPtr p = kst_cast<Kst2DPlot>(w->view()->findChild(_existingPlotName->currentText()));
 	plots.append(p.data());
-	relayout = false;
     } else if (_cycleExisting->isChecked()) {
 	Kst2DPlotList pl = QDeepCopy<Kst2DPlotList>(w->view()->findChildrenType<Kst2DPlot>());
 	for (Kst2DPlotList::Iterator i = pl.begin(); i != pl.end(); ++i) {
 	    plots += (*i).data();
 	}
-	relayout = false;
     } else { /* cycle */
 	Kst2DPlotPtr p;
 	for (int i = 0; i < _plotNumber->value(); ++i) {
@@ -932,16 +921,25 @@
     }
 
     if (_reGrid->isChecked()) {
-	w->view()->cleanup(_plotColumns->value());
-    } else if (relayout) {
-	if (_radioButtonPlotDataPSD->isChecked()) {
-	    w->view()->cleanup(signed(sqrt(plots.count()/2)));
+        int cols;
+
+        if (_plotColumns->value() == _plotColumns->minValue()) {
+            const KstViewObjectList& children(w->view()->children());
+            int cnt = 0;
+            for (KstViewObjectList::ConstIterator i = children.begin(); i != children.end(); ++i) {
+                if ((*i)->followsFlow()) {
+                    ++cnt;
+                }
+            }
+            cols = int(sqrt(cnt));
 	} else {
-	    w->view()->cleanup(signed(sqrt(plots.count())));
+	    cols = _plotColumns->value();
 	}
+	w->view()->cleanup(cols);
     } else if (w->view()->onGrid()) {
 	w->view()->cleanup(-1);
     }
+
     w->view()->paint(KstPainter::P_PAINT);
     app->slotUpdateProgress(0, 0, QString::null);
     if (!wasPaused) {
@@ -949,7 +947,6 @@
     }
 
     saveSettings();
-
 }
 
 
@@ -1094,6 +1091,7 @@
     cfg.writeEntry("PlotNumber", _plotNumber->value());
 
     cfg.writeEntry("OrderInColumns", _orderInColumns->isChecked());
+    cfg.writeEntry("PlotColumns", _plotColumns->value());
 }
 
 
@@ -1161,6 +1159,7 @@
     _cycleExisting->setChecked(cfg.readBoolEntry("CycleExisting", false));
     _plotNumber->setValue(cfg.readNumEntry("PlotNumber", 2));
     _orderInColumns->setChecked(cfg.readBoolEntry("OrderInColumns", false));
+    _plotColumns->setValue(cfg.readNumEntry("PlotColumns", 0));
 }
 
 
@@ -1333,35 +1332,15 @@
 
 double DataWizard::getFontSize(int count, KstViewWindow *w) {
   double size;
-  double rows, cols;
 
   // if there are already plots in the window, use the the first one's font size.
   Kst2DPlotList plotList = w->view()->findChildrenType<Kst2DPlot>(false);
   if (!plotList.isEmpty()) {
-    return(plotList[0]->xTickLabel()->fontSize());
-  }
-
-  if (_cycleThrough->isChecked()) {
-    count = _plotNumber->value();
-  } else if (!_multiplePlots->isChecked()) {
-    count = 1;
-  }
-
-  size = (double)KstSettings::globalSettings()->plotFontSize;
-
-  if (_reGrid->isChecked()) {
-    cols = _plotColumns->value();
+    size = plotList[0]->xTickLabel()->fontSize();
   } else {
-    cols = floor(sqrt(double(count)));
+    size = (double)KstSettings::globalSettings()->plotFontSize;
   }
-  rows = cols + int(count - cols * cols) / int(cols);
 
-  size *= (rows + cols)/(cols/rows + rows/cols);
-  size -= (double)KstSettings::globalSettings()->plotFontSize;
-  size *=0.7;
-
-  if (size>22) size = 22;
-
   return size;
 }