=== modified file 'src/ui/dialog/tracedialog.cpp'
--- src/ui/dialog/tracedialog.cpp	2012-09-29 02:57:24 +0000
+++ src/ui/dialog/tracedialog.cpp	2012-09-29 05:18:40 +0000
@@ -26,6 +26,8 @@
 #include <glibmm/i18n.h>
 
 #include "desktop.h"
+#include "desktop-tracker.h"
+#include "selection.h"
 
 #include "trace/potrace/inkscape-potrace.h"
 #include "inkscape.h"
@@ -83,6 +85,11 @@
     void abort();
 
     void previewCallback();
+    void previewLiveCallback();
+    void onSettingsChange();
+
+    void setDesktop(SPDesktop *desktop);
+    void setTargetDesktop(SPDesktop *desktop);
 
     //############ General items
 
@@ -194,11 +201,36 @@
     UI::Widget::Frame     previewFrame;
     Gtk::VBox             previewVBox;
     Gtk::Button           previewButton;
+    Gtk::CheckButton      previewLiveButton;
+    gboolean              previewLive;
     Gtk::Image            previewImage;
 
+    SPDesktop *desktop;
+    DesktopTracker deskTrack;
+    sigc::connection desktopChangeConn;
+    sigc::connection selectChangedConn;
+
 };
 
+void TraceDialogImpl::setDesktop(SPDesktop *desktop)
+{
+    Panel::setDesktop(desktop);
+    deskTrack.setBase(desktop);
+}
 
+void TraceDialogImpl::setTargetDesktop(SPDesktop *desktop)
+{
+    if (this->desktop != desktop) {
+        if (this->desktop) {
+            selectChangedConn.disconnect();
+        }
+        this->desktop = desktop;
+        if (desktop && desktop->selection) {
+            selectChangedConn = desktop->selection->connectChanged(sigc::hide(sigc::mem_fun(*this, &TraceDialogImpl::onSettingsChange)));
+        }
+        onSettingsChange();
+    }
+}
 
 //#########################################################################
 //## E V E N T S
@@ -352,6 +384,16 @@
 //#########################################################################
 
 /**
+ * Callback for when any setting changes
+ */
+void TraceDialogImpl::onSettingsChange()
+{
+    if (previewLive) {
+        previewCallback();
+    }
+}
+
+/**
  * Callback from the Preview button.  Can be called from elsewhere.
  */
 void TraceDialogImpl::previewCallback()
@@ -360,6 +402,16 @@
 }
 
 /**
+ * Callback from the Preview Live button.
+ */
+void TraceDialogImpl::previewLiveCallback()
+{
+    previewLive = previewLiveButton.get_active();
+    previewButton.set_sensitive(!previewLive);
+    onSettingsChange();
+}
+
+/**
  * Default response from the dialog.  Let's intercept it
  */
 void TraceDialogImpl::responseCallback(int response_id)
@@ -418,6 +470,7 @@
     modeBrightnessSpinner.set_value(0.45);
     modeBrightnessBox.pack_end(modeBrightnessSpinner, false, false, MARGIN);
     modeBrightnessSpinner.set_tooltip_text(_("Brightness cutoff for black/white"));
+    modeBrightnessSpinner.get_adjustment()->signal_value_changed().connect( sigc::mem_fun(*this, &TraceDialogImpl::onSettingsChange) );
 
     modeBrightnessSpinnerLabel.set_label(_("_Threshold:"));
     modeBrightnessSpinnerLabel.set_use_underline(true);
@@ -436,6 +489,8 @@
     modeCannyRadioButton.set_use_underline(true);
     modeCannyBox.pack_start(modeCannyRadioButton, false, false, MARGIN);
     modeCannyRadioButton.set_tooltip_text(_("Trace with optimal edge detection by J. Canny's algorithm"));
+    modeCannyRadioButton.signal_clicked().connect( sigc::mem_fun(*this, &TraceDialogImpl::onSettingsChange) );
+
     /*
     modeCannyBox.pack_start(modeCannySeparator);
     modeCannyLoSpinnerLabel.set_label(_("Low"));
@@ -452,6 +507,7 @@
     modeCannyHiSpinner.set_value(0.65);
     modeCannyBox.pack_end(modeCannyHiSpinner, false, false, MARGIN);
     modeCannyHiSpinner.set_tooltip_text(_("Brightness cutoff for adjacent pixels (determines edge thickness)"));
+    modeCannyHiSpinner.get_adjustment()->signal_value_changed().connect( sigc::mem_fun(*this, &TraceDialogImpl::onSettingsChange) );
 
     modeCannyHiSpinnerLabel.set_label(_("T_hreshold:"));
     modeCannyHiSpinnerLabel.set_use_underline(true);
@@ -470,6 +526,7 @@
     modeQuantRadioButton.set_use_underline(true);
     modeQuantBox.pack_start(modeQuantRadioButton, false, false, MARGIN);
     modeQuantRadioButton.set_tooltip_text(_("Trace along the boundaries of reduced colors"));
+    modeQuantRadioButton.signal_clicked().connect( sigc::mem_fun(*this, &TraceDialogImpl::onSettingsChange) );
 
     modeQuantNrColorSpinner.set_digits(0);
     modeQuantNrColorSpinner.set_increments(1.0, 0);
@@ -477,6 +534,7 @@
     modeQuantNrColorSpinner.set_value(8.0);
     modeQuantBox.pack_end(modeQuantNrColorSpinner, false, false, MARGIN);
     modeQuantNrColorSpinner.set_tooltip_text(_("The number of reduced colors"));
+    modeQuantNrColorSpinner.get_adjustment()->signal_value_changed().connect( sigc::mem_fun(*this, &TraceDialogImpl::onSettingsChange) );
 
     modeQuantNrColorLabel.set_label(_("_Colors:"));
     modeQuantNrColorLabel.set_mnemonic_widget(modeQuantNrColorSpinner);
@@ -492,6 +550,7 @@
     modeInvertBox.pack_start(modeInvertButton, false, false, MARGIN);
     modeBrightnessVBox.pack_start(modeInvertBox, false, false, MARGIN);
     modeInvertButton.set_tooltip_text(_("Invert black and white regions"));
+    modeInvertButton.signal_clicked().connect( sigc::mem_fun(*this, &TraceDialogImpl::onSettingsChange) );
 
     modeBrightnessFrame.add(modeBrightnessVBox);
     modePageBox.pack_start(modeBrightnessFrame, false, false, 0);
@@ -505,6 +564,7 @@
     modeMultiScanBrightnessRadioButton.set_use_underline(true);
     modeMultiScanHBox1.pack_start(modeMultiScanBrightnessRadioButton, false, false, MARGIN);
     modeMultiScanBrightnessRadioButton.set_tooltip_text(_("Trace the given number of brightness levels"));
+    modeMultiScanBrightnessRadioButton.signal_clicked().connect( sigc::mem_fun(*this, &TraceDialogImpl::onSettingsChange) );
 
     modeMultiScanNrColorSpinner.set_digits(0);
     modeMultiScanNrColorSpinner.set_increments(1.0, 0);
@@ -516,6 +576,7 @@
     modeMultiScanNrColorLabel.set_mnemonic_widget(modeMultiScanNrColorSpinner);
     modeMultiScanHBox1.pack_end(modeMultiScanNrColorLabel, false, false, MARGIN);
     modeMultiScanNrColorSpinner.set_tooltip_text(_("The desired number of scans"));
+    modeMultiScanNrColorSpinner.get_adjustment()->signal_value_changed().connect( sigc::mem_fun(*this, &TraceDialogImpl::onSettingsChange) );
 
     modeMultiScanVBox.pack_start(modeMultiScanHBox1, false, false, MARGIN);
 
@@ -524,6 +585,7 @@
     modeMultiScanColorRadioButton.set_use_underline(true);
     modeMultiScanHBox2.pack_start(modeMultiScanColorRadioButton, false, false, MARGIN);
     modeMultiScanColorRadioButton.set_tooltip_text(_("Trace the given number of reduced colors"));
+    modeMultiScanColorRadioButton.signal_clicked().connect( sigc::mem_fun(*this, &TraceDialogImpl::onSettingsChange) );
 
     modeMultiScanVBox.pack_start(modeMultiScanHBox2, false, false, MARGIN);
 
@@ -532,6 +594,7 @@
     modeMultiScanMonoRadioButton.set_use_underline(true);
     modeMultiScanHBox3.pack_start(modeMultiScanMonoRadioButton, false, false, MARGIN);
     modeMultiScanMonoRadioButton.set_tooltip_text(_("Same as Colors, but the result is converted to grayscale"));
+    modeMultiScanMonoRadioButton.signal_clicked().connect( sigc::mem_fun(*this, &TraceDialogImpl::onSettingsChange) );
 
     modeMultiScanVBox.pack_start(modeMultiScanHBox3, false, false, MARGIN);
 
@@ -541,6 +604,7 @@
     modeMultiScanSmoothButton.set_active(true);
     modeMultiScanHBox4.pack_start(modeMultiScanSmoothButton, false, false, MARGIN);
     modeMultiScanSmoothButton.set_tooltip_text(_("Apply Gaussian blur to the bitmap before tracing"));
+    modeMultiScanSmoothButton.signal_clicked().connect( sigc::mem_fun(*this, &TraceDialogImpl::onSettingsChange) );
 
     // TRANSLATORS: "Stack" is a verb here
     modeMultiScanStackButton.set_label(_("Stac_k scans"));
@@ -548,6 +612,7 @@
     modeMultiScanStackButton.set_active(true);
     modeMultiScanHBox4.pack_start(modeMultiScanStackButton, false, false, MARGIN);
     modeMultiScanStackButton.set_tooltip_text(_("Stack scans on top of one another (no gaps) instead of tiling (usually with gaps)"));
+    modeMultiScanStackButton.signal_clicked().connect( sigc::mem_fun(*this, &TraceDialogImpl::onSettingsChange) );
 
 
     modeMultiScanBackgroundButton.set_label(_("Remo_ve background"));
@@ -556,6 +621,7 @@
     modeMultiScanHBox4.pack_start(modeMultiScanBackgroundButton, false, false, MARGIN);
     // TRANSLATORS: "Layer" refers to one of the stacked paths in the multiscan
     modeMultiScanBackgroundButton.set_tooltip_text(_("Remove bottom (background) layer when done"));
+    modeMultiScanBackgroundButton.signal_clicked().connect( sigc::mem_fun(*this, &TraceDialogImpl::onSettingsChange) );
 
     modeMultiScanVBox.pack_start(modeMultiScanHBox4, false, false, MARGIN);
 
@@ -578,12 +644,14 @@
     optionsSpecklesButton.set_use_underline(true);
     optionsSpecklesButton.set_tooltip_text(_("Ignore small spots (speckles) in the bitmap"));
     optionsSpecklesButton.set_active(true);
+    optionsSpecklesButton.signal_clicked().connect( sigc::mem_fun(*this, &TraceDialogImpl::onSettingsChange) );
     optionsSpecklesBox.pack_start(optionsSpecklesButton, false, false, MARGIN);
     optionsSpecklesSizeSpinner.set_digits(0);
     optionsSpecklesSizeSpinner.set_increments(1, 0);
     optionsSpecklesSizeSpinner.set_range(0, 1000);
     optionsSpecklesSizeSpinner.set_value(2);
     optionsSpecklesSizeSpinner.set_tooltip_text(_("Speckles of up to this many pixels will be suppressed"));
+    optionsSpecklesSizeSpinner.get_adjustment()->signal_value_changed().connect( sigc::mem_fun(*this, &TraceDialogImpl::onSettingsChange) );
     optionsSpecklesBox.pack_end(optionsSpecklesSizeSpinner, false, false, MARGIN);
     optionsSpecklesSizeLabel.set_label(_("S_ize:"));
     optionsSpecklesSizeLabel.set_use_underline(true);
@@ -594,6 +662,7 @@
     optionsCornersButton.set_use_underline(true);
     optionsCornersButton.set_tooltip_text(_("Smooth out sharp corners of the trace"));
     optionsCornersButton.set_active(true);
+    optionsCornersButton.signal_clicked().connect( sigc::mem_fun(*this, &TraceDialogImpl::onSettingsChange) );
     optionsCornersBox.pack_start(optionsCornersButton, false, false, MARGIN);
     optionsCornersThresholdSpinner.set_digits(2);
     optionsCornersThresholdSpinner.set_increments(0.01, 0);
@@ -601,6 +670,7 @@
     optionsCornersThresholdSpinner.set_value(1.0);
     optionsCornersBox.pack_end(optionsCornersThresholdSpinner, false, false, MARGIN);
     optionsCornersThresholdSpinner.set_tooltip_text(_("Increase this to smooth corners more"));
+    optionsCornersThresholdSpinner.get_adjustment()->signal_value_changed().connect( sigc::mem_fun(*this, &TraceDialogImpl::onSettingsChange) );
     optionsCornersThresholdLabel.set_label(_("_Threshold:"));
     optionsCornersThresholdLabel.set_use_underline(true);
     optionsCornersThresholdLabel.set_mnemonic_widget(optionsCornersThresholdSpinner);
@@ -610,6 +680,7 @@
     optionsOptimButton.set_use_underline(true);
     optionsOptimButton.set_active(true);
     optionsOptimButton.set_tooltip_text(_("Try to optimize paths by joining adjacent Bezier curve segments"));
+    optionsOptimButton.signal_clicked().connect( sigc::mem_fun(*this, &TraceDialogImpl::onSettingsChange) );
     optionsOptimBox.pack_start(optionsOptimButton, false, false, MARGIN);
     optionsOptimToleranceSpinner.set_digits(2);
     optionsOptimToleranceSpinner.set_increments(0.05, 0);
@@ -617,6 +688,7 @@
     optionsOptimToleranceSpinner.set_value(0.2);
     optionsOptimBox.pack_end(optionsOptimToleranceSpinner, false, false, MARGIN);
     optionsOptimToleranceSpinner.set_tooltip_text(_("Increase this to reduce the number of nodes in the trace by more aggressive optimization"));
+    optionsOptimToleranceSpinner.get_adjustment()->signal_value_changed().connect( sigc::mem_fun(*this, &TraceDialogImpl::onSettingsChange) );
     optionsOptimToleranceLabel.set_label(_("To_lerance:"));
     optionsOptimToleranceLabel.set_use_underline(true);
     optionsOptimToleranceLabel.set_mnemonic_widget(optionsOptimToleranceSpinner);
@@ -659,12 +731,20 @@
     rightVBox.pack_start(sioxBox, false, false, 0);
 
     //## preview
+    Gtk::HBox *previewButtonHBox = manage(new Gtk::HBox(false, MARGIN ));
+    previewLiveButton.set_label(_("_Live Preview"));
+    previewLiveButton.set_use_underline(true);
+    previewLiveCallback();
+    previewLiveButton.signal_clicked().connect(
+         sigc::mem_fun(*this, &TraceDialogImpl::previewLiveCallback) );
 
     previewButton.set_label(_("_Update"));
     previewButton.set_use_underline(true);
     previewButton.signal_clicked().connect(
          sigc::mem_fun(*this, &TraceDialogImpl::previewCallback) );
-    previewVBox.pack_end(previewButton, false, false, 0);
+    previewButtonHBox->pack_start(previewLiveButton, false, false, 0);
+    previewButtonHBox->pack_end(previewButton, true, true, 0);
+    previewVBox.pack_end(*previewButtonHBox, false, false, 0);
     // I guess it's correct to call the "intermediate bitmap" a preview of the trace
     previewButton.set_tooltip_text(_("Preview the intermediate bitmap with the current settings, without actual tracing"));
     previewImage.set_size_request(200,200);
@@ -695,6 +775,9 @@
 
     show_all_children();
 
+    desktopChangeConn = deskTrack.connectDesktopChanged( sigc::mem_fun(*this, &TraceDialogImpl::setTargetDesktop) );
+    deskTrack.connect(GTK_WIDGET(gobj()));
+
     //## Connect the signal
     signalResponse().connect(
 	sigc::mem_fun(*this, &TraceDialogImpl::responseCallback));
@@ -715,6 +798,8 @@
  */
 TraceDialogImpl::~TraceDialogImpl()
 {
+    selectChangedConn.disconnect();
+    desktopChangeConn.disconnect();
 
 }