[FEM] check if Gmsh, CCX and Mystran solver binaries exist

- adds the check like we have already for Z88 and Elmer
- also remove an unnecessary return statement

src/Mod/Fem/Gui/DlgSettingsFemCcxImp.cpp

@@ -26,6 +26,7 @@
 #include "PreCompiled.h"
 #ifndef _PreComp_
 # include <thread>
+# include <QMessageBox>
 #endif
 
 #include <Gui/Application.h>
@@ -49,6 +50,9 @@ DlgSettingsFemCcxImp::DlgSettingsFemCcxImp(QWidget* parent)
     // hardware check might fail and then returns 0
     if (processor_count > 0)
         ui->sb_ccx_numcpu->setMaximum(processor_count);
+
+    connect(ui->fc_ccx_binary_path, &Gui::PrefFileChooser::fileNameChanged,
+            this, &DlgSettingsFemCcxImp::onfileNameChanged);
 }
 
 DlgSettingsFemCcxImp::~DlgSettingsFemCcxImp()
@@ -135,4 +139,13 @@ void DlgSettingsFemCcxImp::changeEvent(QEvent* e)
     }
 }
 
+void DlgSettingsFemCcxImp::onfileNameChanged(QString FileName)
+{
+    if (!QFileInfo::exists(FileName)) {
+        QMessageBox::critical(this, tr("File does not exist"),
+                              tr("The specified executable \n'%1'\n does not exist!\n"
+                                 "Specify another file please.").arg(FileName));
+    }
+}
+
 #include "moc_DlgSettingsFemCcxImp.cpp"

src/Mod/Fem/Gui/DlgSettingsFemCcxImp.h

@@ -40,6 +40,9 @@ public:
     DlgSettingsFemCcxImp( QWidget* parent = nullptr );
     ~DlgSettingsFemCcxImp();
 
+protected Q_SLOTS:
+    void onfileNameChanged(QString FileName);
+
 protected:
     void saveSettings();
     void loadSettings();

src/Mod/Fem/Gui/DlgSettingsFemElmerImp.cpp

@@ -102,7 +102,6 @@ void DlgSettingsFemElmerImp::onfileNameChanged(QString FileName)
         QMessageBox::critical(this, tr("File does not exist"),
                               tr("The specified executable \n'%1'\n does not exist!\n"
                                  "Specify another file please.").arg(FileName));
-        return;
     }
 }
 

src/Mod/Fem/Gui/DlgSettingsFemGmshImp.cpp

@@ -23,6 +23,9 @@
  ***************************************************************************/
 
 #include "PreCompiled.h"
+#ifndef _PreComp_
+# include <QMessageBox>
+#endif
 
 #include "DlgSettingsFemGmshImp.h"
 #include "ui_DlgSettingsFemGmsh.h"
@@ -35,6 +38,9 @@ DlgSettingsFemGmshImp::DlgSettingsFemGmshImp(QWidget* parent)
     , ui(new Ui_DlgSettingsFemGmshImp)
 {
     ui->setupUi(this);
+
+    connect(ui->fc_gmsh_binary_path, &Gui::PrefFileChooser::fileNameChanged,
+            this, &DlgSettingsFemGmshImp::onfileNameChanged);
 }
 
 DlgSettingsFemGmshImp::~DlgSettingsFemGmshImp()
@@ -67,4 +73,13 @@ void DlgSettingsFemGmshImp::changeEvent(QEvent* e)
     }
 }
 
+void DlgSettingsFemGmshImp::onfileNameChanged(QString FileName)
+{
+    if (!QFileInfo::exists(FileName)) {
+        QMessageBox::critical(this, tr("File does not exist"),
+                              tr("The specified executable \n'%1'\n does not exist!\n"
+                                 "Specify another file please.").arg(FileName));
+    }
+}
+
 #include "moc_DlgSettingsFemGmshImp.cpp"

src/Mod/Fem/Gui/DlgSettingsFemGmshImp.h

@@ -39,6 +39,9 @@ public:
     DlgSettingsFemGmshImp( QWidget* parent = nullptr );
     ~DlgSettingsFemGmshImp();
 
+protected Q_SLOTS:
+    void onfileNameChanged(QString FileName);
+
 protected:
     void saveSettings();
     void loadSettings();

src/Mod/Fem/Gui/DlgSettingsFemMystranImp.cpp

@@ -23,6 +23,9 @@
  ***************************************************************************/
 
 #include "PreCompiled.h"
+#ifndef _PreComp_
+# include <QMessageBox>
+#endif
 
 #include "DlgSettingsFemMystranImp.h"
 #include "ui_DlgSettingsFemMystran.h"
@@ -35,6 +38,9 @@ DlgSettingsFemMystranImp::DlgSettingsFemMystranImp(QWidget* parent)
     , ui(new Ui_DlgSettingsFemMystranImp)
 {
     ui->setupUi(this);
+
+    connect(ui->fc_mystran_binary_path, &Gui::PrefFileChooser::fileNameChanged,
+            this, &DlgSettingsFemMystranImp::onfileNameChanged);
 }
 
 DlgSettingsFemMystranImp::~DlgSettingsFemMystranImp()
@@ -69,4 +75,13 @@ void DlgSettingsFemMystranImp::changeEvent(QEvent* e)
     }
 }
 
+void DlgSettingsFemMystranImp::onfileNameChanged(QString FileName)
+{
+    if (!QFileInfo::exists(FileName)) {
+        QMessageBox::critical(this, tr("File does not exist"),
+                              tr("The specified executable \n'%1'\n does not exist!\n"
+                                 "Specify another file please.").arg(FileName));
+    }
+}
+
 #include "moc_DlgSettingsFemMystranImp.cpp"

src/Mod/Fem/Gui/DlgSettingsFemMystranImp.h

@@ -40,6 +40,9 @@ public:
     DlgSettingsFemMystranImp( QWidget* parent = nullptr );
     ~DlgSettingsFemMystranImp();
 
+protected Q_SLOTS:
+    void onfileNameChanged(QString FileName);
+
 protected:
     void saveSettings();
     void loadSettings();