Fixes issue when deleting locallab tool with mask preview active

rtgui/locallabtools2.cc

@@ -254,6 +254,11 @@ LocallabTone::~LocallabTone()
     delete mask2tmCurveEditorG;
 }
 
+bool LocallabTone::isMaskViewActive()
+{
+    return (showmasktmMethod->get_active_row_number() != 0);
+}
+
 void LocallabTone::resetMaskView()
 {
     showmasktmMethodConn.block(true);
@@ -984,6 +989,11 @@ void LocallabRetinex::updateMinMax(const double cdma, const double cdmin, const
     );
 }
 
+bool LocallabRetinex::isMaskViewActive()
+{
+    return (showmaskretiMethod->get_active_row_number() != 0);
+}
+
 void LocallabRetinex::resetMaskView()
 {
     showmaskretiMethodConn.block(true);
@@ -1769,6 +1779,11 @@ LocallabSharp::LocallabSharp():
     pack_start(*sharFrame);
 }
 
+bool LocallabSharp::isMaskViewActive()
+{
+    return (showmasksharMethod->get_active_row_number() != 0);
+}
+
 void LocallabSharp::resetMaskView()
 {
     showmasksharMethodConn.block(true);
@@ -2501,6 +2516,11 @@ LocallabContrast::~LocallabContrast()
     delete mask2lcCurveEditorG;
 }
 
+bool LocallabContrast::isMaskViewActive()
+{
+    return (showmasklcMethod->get_active_row_number() != 0);
+}
+
 void LocallabContrast::resetMaskView()
 {
     showmasklcMethodConn.block(true);
@@ -3804,6 +3824,12 @@ LocallabCBDL::~LocallabCBDL()
     delete mask2cbCurveEditorG;
 }
 
+bool LocallabCBDL::isMaskViewActive()
+{
+    return (showmaskcbMethod->get_active_row_number() != 0);
+}
+
+
 void LocallabCBDL::resetMaskView()
 {
     showmaskcbMethodConn.block(true);