[Qt] coin-control features GUI cleanup 2

- remove monospace labels from sendcoinsdialog also
- use a validated line edit for the change address
- add a tooltip to change address switch
- ensure we have a valid change address in
  CoinControlDialog::coinControl->destChange or just CNoDestination()
- some small ui file changes

src/qt/forms/sendcoinsdialog.ui

@@ -39,7 +39,7 @@
      </property>
      <layout class="QVBoxLayout" name="verticalLayoutCoinControl2">
       <property name="spacing">
-       <number>-1</number>
+       <number>0</number>
       </property>
       <property name="leftMargin">
        <number>0</number>
@@ -173,7 +173,16 @@
            <string notr="true"/>
           </property>
           <layout class="QHBoxLayout" name="horizontalLayoutCoinControl5">
-           <property name="margin">
+           <property name="leftMargin">
+            <number>0</number>
+           </property>
+           <property name="topMargin">
+            <number>0</number>
+           </property>
+           <property name="rightMargin">
+            <number>0</number>
+           </property>
+           <property name="bottomMargin">
             <number>0</number>
            </property>
            <item>
@@ -219,12 +228,6 @@
                </item>
                <item row="0" column="1">
                 <widget class="QLabel" name="labelCoinControlQuantity">
-                 <property name="font">
-                  <font>
-                   <family>Monospace</family>
-                   <pointsize>10</pointsize>
-                  </font>
-                 </property>
                  <property name="cursor">
                   <cursorShape>IBeamCursor</cursorShape>
                  </property>
@@ -254,12 +257,6 @@
                </item>
                <item row="1" column="1">
                 <widget class="QLabel" name="labelCoinControlBytes">
-                 <property name="font">
-                  <font>
-                   <family>Monospace</family>
-                   <pointsize>10</pointsize>
-                  </font>
-                 </property>
                  <property name="cursor">
                   <cursorShape>IBeamCursor</cursorShape>
                  </property>
@@ -308,12 +305,6 @@
                </item>
                <item row="0" column="1">
                 <widget class="QLabel" name="labelCoinControlAmount">
-                 <property name="font">
-                  <font>
-                   <family>Monospace</family>
-                   <pointsize>10</pointsize>
-                  </font>
-                 </property>
                  <property name="cursor">
                   <cursorShape>IBeamCursor</cursorShape>
                  </property>
@@ -340,12 +331,6 @@
                </item>
                <item row="1" column="1">
                 <widget class="QLabel" name="labelCoinControlPriority">
-                 <property name="font">
-                  <font>
-                   <family>Monospace</family>
-                   <pointsize>10</pointsize>
-                  </font>
-                 </property>
                  <property name="cursor">
                   <cursorShape>IBeamCursor</cursorShape>
                  </property>
@@ -394,12 +379,6 @@
                </item>
                <item row="0" column="1">
                 <widget class="QLabel" name="labelCoinControlFee">
-                 <property name="font">
-                  <font>
-                   <family>Monospace</family>
-                   <pointsize>10</pointsize>
-                  </font>
-                 </property>
                  <property name="cursor">
                   <cursorShape>IBeamCursor</cursorShape>
                  </property>
@@ -426,12 +405,6 @@
                </item>
                <item row="1" column="1">
                 <widget class="QLabel" name="labelCoinControlLowOutput">
-                 <property name="font">
-                  <font>
-                   <family>Monospace</family>
-                   <pointsize>10</pointsize>
-                  </font>
-                 </property>
                  <property name="cursor">
                   <cursorShape>IBeamCursor</cursorShape>
                  </property>
@@ -480,12 +453,6 @@
                </item>
                <item row="0" column="1">
                 <widget class="QLabel" name="labelCoinControlAfterFee">
-                 <property name="font">
-                  <font>
-                   <family>Monospace</family>
-                   <pointsize>10</pointsize>
-                  </font>
-                 </property>
                  <property name="cursor">
                   <cursorShape>IBeamCursor</cursorShape>
                  </property>
@@ -512,12 +479,6 @@
                </item>
                <item row="1" column="1">
                 <widget class="QLabel" name="labelCoinControlChange">
-                 <property name="font">
-                  <font>
-                   <family>Monospace</family>
-                   <pointsize>10</pointsize>
-                  </font>
-                 </property>
                  <property name="cursor">
                   <cursorShape>IBeamCursor</cursorShape>
                  </property>
@@ -555,13 +516,16 @@
           </property>
           <item>
            <widget class="QCheckBox" name="checkBoxCoinControlChange">
+            <property name="toolTip">
+             <string>If this is activated, but the change address is empty or invalid, change will be sent to a newly generated address.</string>
+            </property>
             <property name="text">
-             <string>custom change address</string>
+             <string>Custom change address</string>
             </property>
            </widget>
           </item>
           <item>
-           <widget class="QLineEdit" name="lineEditCoinControlChange">
+           <widget class="QValidatedLineEdit" name="lineEditCoinControlChange">
             <property name="enabled">
              <bool>false</bool>
             </property>
@@ -626,7 +590,7 @@
         <x>0</x>
         <y>0</y>
         <width>830</width>
-        <height>165</height>
+        <height>178</height>
        </rect>
       </property>
       <layout class="QVBoxLayout" name="verticalLayout_2" stretch="0,1">
@@ -778,6 +742,13 @@
    </item>
   </layout>
  </widget>
+ <customwidgets>
+  <customwidget>
+   <class>QValidatedLineEdit</class>
+   <extends>QLineEdit</extends>
+   <header>qvalidatedlineedit.h</header>
+  </customwidget>
+ </customwidgets>
  <resources>
   <include location="../bitcoin.qrc"/>
  </resources>

src/qt/sendcoinsdialog.cpp

@@ -529,16 +529,17 @@ void SendCoinsDialog::coinControlButtonClicked()
 // Coin Control: checkbox custom change address
 void SendCoinsDialog::coinControlChangeChecked(int state)
 {
-    if (model)
+    if (state == Qt::Unchecked)
     {
-        if (state == Qt::Checked)
-            CoinControlDialog::coinControl->destChange = CBitcoinAddress(ui->lineEditCoinControlChange->text().toStdString()).Get();
-        else
         CoinControlDialog::coinControl->destChange = CNoDestination();
+        ui->lineEditCoinControlChange->setValid(true);
+        ui->labelCoinControlChangeLabel->clear();
     }
+    else
+        // use this to re-validate an already entered address
+        coinControlChangeEdited(ui->lineEditCoinControlChange->text());
 
     ui->lineEditCoinControlChange->setEnabled((state == Qt::Checked));
-    ui->labelCoinControlChangeLabel->setVisible((state == Qt::Checked));
 }
 
 // Coin Control: custom change address changed
@@ -554,6 +555,10 @@ void SendCoinsDialog::coinControlChangeEdited(const QString & text)
             ui->labelCoinControlChangeLabel->setText("");
         else if (!CBitcoinAddress(text.toStdString()).IsValid())
         {
+            // invalid change address
+            CoinControlDialog::coinControl->destChange = CNoDestination();
+
+            ui->lineEditCoinControlChange->setValid(false);
             ui->labelCoinControlChangeLabel->setStyleSheet("QLabel{color:red;}");
             ui->labelCoinControlChangeLabel->setText(tr("Warning: Invalid Bitcoin address"));
         }
@@ -571,6 +576,10 @@ void SendCoinsDialog::coinControlChangeEdited(const QString & text)
                     ui->labelCoinControlChangeLabel->setText(tr("(no label)"));
                 else
                 {
+                    // unknown change address
+                    CoinControlDialog::coinControl->destChange = CNoDestination();
+
+                    ui->lineEditCoinControlChange->setValid(false);
                     ui->labelCoinControlChangeLabel->setStyleSheet("QLabel{color:red;}");
                     ui->labelCoinControlChangeLabel->setText(tr("Warning: Unknown change address"));
                 }