diff --git a/bundles/org.openhab.ui/web/src/assets/items-lexer.nearley b/bundles/org.openhab.ui/web/src/assets/items-lexer.nearley
index 887daa2457..7c793c0eef 100644
--- a/bundles/org.openhab.ui/web/src/assets/items-lexer.nearley
+++ b/bundles/org.openhab.ui/web/src/assets/items-lexer.nearley
@@ -9,7 +9,7 @@
     itemtype:   ['Group ', 'Number ', 'Switch ', 'Rollershutter ', 'String ', 'Dimmer ', 'Contact ', 'DateTime ', 'Color ', 'Player ', 'Location ', 'Call ', 'Image '],
     membertype: [':Number', ':Switch', ':Rollershutter', ':String', ':Dimmer', ':Contact', ':DateTime', ':Color', ':Player', ':Location', ':Call', ':Image'],
     aggfunc:    ['AVG', 'SUM', 'MIN', 'MAX', 'OR', 'AND', 'COUNT', 'LATEST', 'EARLIEST', 'EQUALITY'],
-    identifier: /[A-Za-z0-9_-]+/,
+    identifier: /(?:[A-Za-z_][A-Za-z0-9_]*)|(?:[0-9]+[A-Za-z_][A-Za-z0-9_]*)/,
     lparen:     '(',
     rparen:     ')',
     colon:      ':',
@@ -21,6 +21,8 @@
     gt:         '>',
     comma:      ',',
     equals:     '=',
+    colon:      ':',
+    hyphen:     '-',
     NL:         { match: /\n/, lineBreaks: true },
   })
 %}
@@ -54,7 +56,7 @@ Type -> %itemtype                                   {% (d) => [d[0].text.trim()]
   | "Group" %membertype                             {% (d) => ['Group', d[1].text.substring(1)] %}
   | "Group" %membertype ":" %aggfunc AggArgs        {% (d) => ['Group', d[1].text.substring(1), {name: d[3].text, params: d[4]}] %}
   | "Group" %membertype ":" %identifier             {% (d) => ['Group', 'Number:' + d[3].text] %}
-  | "Group" %membertype ":" %identifier ":" %aggfunc AggArgs     {% (d) => ['Group', 'Number:' + d[3].text, {name: d[5].text, params: d[6]}] %}
+  | "Group" %membertype ":" %identifier ":" %aggfunc AggArgs   {% (d) => ['Group', 'Number:' + d[3].text, {name: d[5].text, params: d[6]}] %}
 # group function aggregation arguments
 AggArgs -> null                                     {% (d) => undefined %}
   | "(" %identifier ")"                             {% (d) => [d[1].text] %}
@@ -69,7 +71,13 @@ Label -> null                                       {% (d) => undefined %}
 
 # Icon (category)
 Icon -> null                                        {% (d) => undefined %}
-  | __ "<" _ %identifier _ ">"                      {% (d) => d[3].text %}
+  | __ "<" _ IconValue _ ">"                        {% (d) => d[3].join("") %}
+IconValue -> %string
+  | IconName
+  | %identifier %colon IconName
+  | %identifier %colon %identifier %colon IconName
+IconName -> %identifier
+  | %identifier %hyphen IconName                    {% (d) => d[0].value + "-" + d[2] %}
 
 # Groups
 Groups -> null                                      {% (d) => undefined %}
@@ -107,14 +115,14 @@ MetadataConfigValue -> %string                      {% (d) => d[0].value %}
   | %number                                         {% (d) => parseInt(d[0].value) %}
 
 
-_ -> null {% () => null %}
-  | _ %WS  {% () => null %}
-  | _ %NL  {% () => null %}
+_ -> null      {% () => null %}
+  | _ %WS      {% () => null %}
+  | _ %NL      {% () => null %}
   | _ %comment {% () => null %}
 
-__ -> %WS      {% () => null %}
-  | %NL      {% () => null %}
+__ -> %WS       {% () => null %}
+  | %NL         {% () => null %}
   | %comment    {% () => null %}
   | __ %WS      {% () => null %}
   | __ %NL      {% () => null %}
-  | __ %comment   {% () => null %}
+  | __ %comment {% () => null %}
diff --git a/bundles/org.openhab.ui/web/src/assets/sitemap-lexer.nearley b/bundles/org.openhab.ui/web/src/assets/sitemap-lexer.nearley
index dd53571024..ad87af4bea 100644
--- a/bundles/org.openhab.ui/web/src/assets/sitemap-lexer.nearley
+++ b/bundles/org.openhab.ui/web/src/assets/sitemap-lexer.nearley
@@ -33,6 +33,8 @@
     gt:               '>',
     equals:           '=',
     comma:            ',',
+    colon:            ':',
+    hyphen:           '-',
     NL:               { match: /\n/, lineBreaks: true },
     boolean:          /(?:true)|(?:false)/,
     identifier:       /(?:[A-Za-z_][A-Za-z0-9_]*)|(?:[0-9]+[A-Za-z_][A-Za-z0-9_]*)/,
@@ -99,12 +101,19 @@ WidgetAttr -> %widgetswitchattr
   | %widgetfrcitmattr WidgetBooleanAttrValue                                      {% (d) => ['forceAsItem', d[1]] %}
   | %widgetboolattr WidgetBooleanAttrValue                                        {% (d) => [d[0].value, d[1]] %}
   | %widgetfreqattr WidgetAttrValue                                               {% (d) => ['frequency', d[1]] %}
+  | %icon WidgetIconAttrValue                                                     {% (d) => [d[0].value, d[1].join("")] %}
   | WidgetAttrName WidgetAttrValue                                                {% (d) => [d[0][0].value, d[1]] %}
   | WidgetVisibilityAttrName WidgetVisibilityAttrValue                            {% (d) => [d[0][0].value, d[1]] %}
   | WidgetColorAttrName WidgetColorAttrValue                                      {% (d) => [d[0][0].value, d[1]] %}
-WidgetAttrName -> %item | %label | %icon | %widgetattr
+WidgetAttrName -> %item | %label | %widgetattr
 WidgetBooleanAttrValue -> %boolean                                                {% (d) => (d[0].value === 'true') %}
   | %string                                                                       {% (d) => (d[0].value === 'true') %}
+WidgetIconAttrValue -> %string
+  | WidgetIconName
+  | %identifier %colon WidgetIconName
+  | %identifier %colon %identifier %colon WidgetIconName
+WidgetIconName -> %identifier
+  | %identifier %hyphen WidgetIconName                                            {% (d) => d[0].value + "-" + d[2] %}
 WidgetAttrValue -> %number                                                        {% (d) => { return parseFloat(d[0].value) } %}
   | %identifier                                                                   {% (d) => d[0].value %}
   | %string                                                                       {% (d) => d[0].value %}
diff --git a/bundles/org.openhab.ui/web/src/components/pagedesigner/sitemap/__tests__/sitemap-code_jest.spec.js b/bundles/org.openhab.ui/web/src/components/pagedesigner/sitemap/__tests__/sitemap-code_jest.spec.js
index bdc587d501..0c69ae7040 100644
--- a/bundles/org.openhab.ui/web/src/components/pagedesigner/sitemap/__tests__/sitemap-code_jest.spec.js
+++ b/bundles/org.openhab.ui/web/src/components/pagedesigner/sitemap/__tests__/sitemap-code_jest.spec.js
@@ -102,10 +102,57 @@ describe('SitemapCode', () => {
     })
   })
 
+  it('parses a segmented icon name with hyphens', async () => {
+    expect(wrapper.vm.sitemapDsl).toBeDefined()
+    // simulate updating the sitemap in code
+    const sitemap = [
+      'sitemap test label="Test" {',
+      '    Default item=Item_Icon icon=iconify:wi:day-sunny-overcast',
+      '    Default item=Item_Icon_String icon="iconify:wi:day-sunny-overcast"',
+      '}',
+      ''
+    ].join('\n')
+    wrapper.vm.updateSitemap(sitemap)
+    expect(wrapper.vm.sitemapDsl).toMatch(/^sitemap test label="Test"/)
+    expect(wrapper.vm.parsedSitemap.error).toBeFalsy()
+
+    await wrapper.vm.$nextTick()
+
+    // check whether an 'updated' event was emitted and its payload
+    // (should contain the parsing result for the new sitemap definition)
+    const events = wrapper.emitted().updated
+    expect(events).toBeTruthy()
+    expect(events.length).toBe(1)
+    const payload = events[0][0]
+    expect(payload.slots).toBeDefined()
+    expect(payload.slots.widgets).toBeDefined()
+    expect(payload.slots.widgets.length).toBe(2)
+    expect(payload.slots.widgets[0]).toEqual({
+      component: 'Default',
+      config: {
+        item: 'Item_Icon',
+        icon: 'iconify:wi:day-sunny-overcast'
+      }
+    })
+    expect(payload.slots.widgets[1]).toEqual({
+      component: 'Default',
+      config: {
+        item: 'Item_Icon_String',
+        icon: 'iconify:wi:day-sunny-overcast'
+      }
+    })
+  })
+
   it('parses a mapping code back to a mapping on a component', async () => {
     expect(wrapper.vm.sitemapDsl).toBeDefined()
     // simulate updating the sitemap in code
-    wrapper.vm.updateSitemap('sitemap test label="Test" {\n    Selection item=Scene_General mappings=[1=Morning,2="Evening",10="Cinéma",11=TV,3="Bed time",4=Night]\n}\n')
+    const sitemap = [
+      'sitemap test label="Test" {',
+      '    Selection item=Scene_General mappings=[1=Morning,2="Evening",10="Cinéma",11=TV,3="Bed time",4=Night]',
+      '}',
+      ''
+    ].join('\n')
+    wrapper.vm.updateSitemap(sitemap)
     expect(wrapper.vm.sitemapDsl).toMatch(/^sitemap test label="Test"/)
     expect(wrapper.vm.parsedSitemap.error).toBeFalsy()
 
diff --git a/bundles/org.openhab.ui/web/src/css/app.styl b/bundles/org.openhab.ui/web/src/css/app.styl
index 2f7d7ca505..643a3716a9 100644
--- a/bundles/org.openhab.ui/web/src/css/app.styl
+++ b/bundles/org.openhab.ui/web/src/css/app.styl
@@ -292,3 +292,6 @@ html
   --f7-toast-text-color white
   --f7-button-text-color white
   --f7-button-border-color white
+
+.sitemap-validation-dialog
+  --f7-dialog-width 80%
diff --git a/bundles/org.openhab.ui/web/src/pages/settings/pages/sitemap/__tests__/sitemap-edit_jest.spec.js b/bundles/org.openhab.ui/web/src/pages/settings/pages/sitemap/__tests__/sitemap-edit_jest.spec.js
index d2ead7e632..758b1588ba 100644
--- a/bundles/org.openhab.ui/web/src/pages/settings/pages/sitemap/__tests__/sitemap-edit_jest.spec.js
+++ b/bundles/org.openhab.ui/web/src/pages/settings/pages/sitemap/__tests__/sitemap-edit_jest.spec.js
@@ -46,10 +46,83 @@ describe('SitemapEdit', () => {
     expect(wrapper.vm.sitemap.component).toEqual('Sitemap')
   })
 
+  it('validates frame does not contain frames', async () => {
+    wrapper.vm.selectWidget([wrapper.vm.sitemap, null])
+    await wrapper.vm.$nextTick()
+    wrapper.vm.addWidget('Frame')
+    await wrapper.vm.$nextTick()
+    wrapper.vm.selectWidget([wrapper.vm.sitemap.slots.widgets[0], wrapper.vm.sitemap])
+    await wrapper.vm.$nextTick()
+    wrapper.vm.addWidget('Frame')
+    await wrapper.vm.$nextTick()
+    wrapper.vm.selectWidget([wrapper.vm.sitemap.slots.widgets[0].slots.widgets[0], wrapper.vm.sitemap])
+    await wrapper.vm.$nextTick()
+    localVue.set(wrapper.vm.selectedWidget.config, 'label', 'Frame Test')
+
+    // should not validate as the frame contains a frame
+    lastDialogConfig = null
+    wrapper.vm.validateWidgets()
+    expect(lastDialogConfig).toBeTruthy()
+    expect(lastDialogConfig.content).toMatch(/Frame widget Frame Test, frame not allowed in frame/)
+  })
+
+  it('validates frame in text does not contain frames', async () => {
+    wrapper.vm.selectWidget([wrapper.vm.sitemap, null])
+    await wrapper.vm.$nextTick()
+    wrapper.vm.addWidget('Frame')
+    await wrapper.vm.$nextTick()
+    wrapper.vm.selectWidget([wrapper.vm.sitemap.slots.widgets[0], wrapper.vm.sitemap])
+    await wrapper.vm.$nextTick()
+    wrapper.vm.addWidget('Text')
+    await wrapper.vm.$nextTick()
+    wrapper.vm.selectWidget([wrapper.vm.sitemap.slots.widgets[0].slots.widgets[0], wrapper.vm.sitemap])
+    await wrapper.vm.$nextTick()
+    wrapper.vm.addWidget('Frame')
+    await wrapper.vm.$nextTick()
+
+    // should validate, as frame in text in frame is allowed
+    lastDialogConfig = null
+    wrapper.vm.validateWidgets()
+    expect(lastDialogConfig).toBeFalsy()
+
+    // add a frame inside the frame in the text
+    wrapper.vm.selectWidget([wrapper.vm.sitemap.slots.widgets[0].slots.widgets[0].slots.widgets[0], wrapper.vm.sitemap])
+    await wrapper.vm.$nextTick()
+    wrapper.vm.addWidget('Frame')
+    await wrapper.vm.$nextTick()
+    wrapper.vm.selectWidget([wrapper.vm.sitemap.slots.widgets[0].slots.widgets[0].slots.widgets[0].slots.widgets[0], wrapper.vm.sitemap])
+    await wrapper.vm.$nextTick()
+    localVue.set(wrapper.vm.selectedWidget.config, 'label', 'Frame Test')
+
+    // should not validate as the frame contains a frame
+    lastDialogConfig = null
+    wrapper.vm.validateWidgets()
+    expect(lastDialogConfig).toBeTruthy()
+    expect(lastDialogConfig.content).toMatch(/Frame widget Frame Test, frame not allowed in frame/)
+  })
+
+  it('validates only frames or no frames at all', async () => {
+    wrapper.vm.selectWidget([wrapper.vm.sitemap, null])
+    await wrapper.vm.$nextTick()
+    wrapper.vm.addWidget('Frame')
+    await wrapper.vm.$nextTick()
+    wrapper.vm.selectWidget([wrapper.vm.sitemap, null])
+    await wrapper.vm.$nextTick()
+    wrapper.vm.addWidget('Text')
+    await wrapper.vm.$nextTick()
+
+    // should not validate as mix of frame and text
+    lastDialogConfig = null
+    wrapper.vm.validateWidgets()
+    expect(lastDialogConfig).toBeTruthy()
+    expect(lastDialogConfig.content).toMatch(/Widget without label, only frames or no frames at all allowed in linkable widget/)
+  })
+
   it('validates item name is checked', async () => {
     wrapper.vm.selectWidget([wrapper.vm.sitemap, null])
     await wrapper.vm.$nextTick()
     wrapper.vm.addWidget('Frame')
+    await wrapper.vm.$nextTick()
     wrapper.vm.selectWidget([wrapper.vm.sitemap.slots.widgets[0], wrapper.vm.sitemap])
     await wrapper.vm.$nextTick()
     wrapper.vm.addWidget('Switch')
@@ -94,7 +167,7 @@ describe('SitemapEdit', () => {
     expect(lastDialogConfig).toBeFalsy()
   })
 
-  it('validates period is checked', async () => {
+  it('validates period is configured and valid', async () => {
     wrapper.vm.selectWidget([wrapper.vm.sitemap, null])
     await wrapper.vm.$nextTick()
     wrapper.vm.addWidget('Chart')
@@ -108,7 +181,16 @@ describe('SitemapEdit', () => {
     lastDialogConfig = null
     wrapper.vm.validateWidgets()
     expect(lastDialogConfig).toBeTruthy()
-    expect(lastDialogConfig.content).toMatch(/Chart widget Chart Test, no period configured/)
+    expect(lastDialogConfig.content).toMatch(/Chart widget Chart Test, invalid period configured: undefined/)
+
+    // configure an invalid period for the Chart
+    lastDialogConfig = null
+    wrapper.vm.selectWidget([wrapper.vm.sitemap.slots.widgets[0], wrapper.vm.sitemap])
+    await wrapper.vm.$nextTick()
+    localVue.set(wrapper.vm.selectedWidget.config, 'period', '5h')
+    wrapper.vm.validateWidgets()
+    expect(lastDialogConfig).toBeTruthy()
+    expect(lastDialogConfig.content).toMatch(/Chart widget Chart Test, invalid period configured: 5h/)
 
     // configure a period for the Chart and check that there are no validation errors anymore
     lastDialogConfig = null
@@ -119,6 +201,88 @@ describe('SitemapEdit', () => {
     expect(lastDialogConfig).toBeFalsy()
   })
 
+  it('validates step is positive', async () => {
+    wrapper.vm.selectWidget([wrapper.vm.sitemap, null])
+    await wrapper.vm.$nextTick()
+    wrapper.vm.addWidget('Slider')
+    await wrapper.vm.$nextTick()
+    wrapper.vm.selectWidget([wrapper.vm.sitemap.slots.widgets[0], wrapper.vm.sitemap])
+    await wrapper.vm.$nextTick()
+    localVue.set(wrapper.vm.selectedWidget.config, 'item', 'Item1')
+    localVue.set(wrapper.vm.selectedWidget.config, 'label', 'Slider Test')
+
+    // no step, should validate
+    lastDialogConfig = null
+    wrapper.vm.validateWidgets()
+    expect(lastDialogConfig).toBeFalsy()
+
+    // configure a negative step, should not validate
+    wrapper.vm.selectWidget([wrapper.vm.sitemap.slots.widgets[0], wrapper.vm.sitemap])
+    await wrapper.vm.$nextTick()
+    localVue.set(wrapper.vm.selectedWidget.config, 'step', -1)
+    lastDialogConfig = null
+    wrapper.vm.validateWidgets()
+    expect(lastDialogConfig).toBeTruthy()
+    expect(lastDialogConfig.content).toMatch(/Slider widget Slider Test, step size cannot be 0 or negative: -1/)
+
+    // configure a 0 step, should not validate
+    wrapper.vm.selectWidget([wrapper.vm.sitemap.slots.widgets[0], wrapper.vm.sitemap])
+    await wrapper.vm.$nextTick()
+    localVue.set(wrapper.vm.selectedWidget.config, 'step', 0)
+    lastDialogConfig = null
+    wrapper.vm.validateWidgets()
+    expect(lastDialogConfig).toBeTruthy()
+    expect(lastDialogConfig.content).toMatch(/Slider widget Slider Test, step size cannot be 0 or negative: 0/)
+
+    // configure a positive step, should validate
+    wrapper.vm.selectWidget([wrapper.vm.sitemap.slots.widgets[0], wrapper.vm.sitemap])
+    await wrapper.vm.$nextTick()
+    localVue.set(wrapper.vm.selectedWidget.config, 'step', 5)
+    lastDialogConfig = null
+    wrapper.vm.validateWidgets()
+    expect(lastDialogConfig).toBeFalsy()
+  })
+
+  it('validates minValue less than or equal maxValue', async () => {
+    wrapper.vm.selectWidget([wrapper.vm.sitemap, null])
+    await wrapper.vm.$nextTick()
+    wrapper.vm.addWidget('Setpoint')
+    await wrapper.vm.$nextTick()
+    wrapper.vm.selectWidget([wrapper.vm.sitemap.slots.widgets[0], wrapper.vm.sitemap])
+    await wrapper.vm.$nextTick()
+    localVue.set(wrapper.vm.selectedWidget.config, 'item', 'Item1')
+    localVue.set(wrapper.vm.selectedWidget.config, 'label', 'Setpoint Test')
+
+    // no minValue or maxValue, should validate
+    lastDialogConfig = null
+    wrapper.vm.validateWidgets()
+    expect(lastDialogConfig).toBeFalsy()
+
+    // configure a minValue more than maxValue, should not validate
+    lastDialogConfig = null
+    localVue.set(wrapper.vm.selectedWidget.config, 'minValue', 10)
+    localVue.set(wrapper.vm.selectedWidget.config, 'maxValue', 5)
+    wrapper.vm.validateWidgets()
+    expect(lastDialogConfig).toBeTruthy()
+    expect(lastDialogConfig.content).toMatch(/Setpoint widget Setpoint Test, minValue must be less than or equal maxValue: 10 > 5/)
+
+    // configure a minValue equal to maxValue, should validate
+    lastDialogConfig = null
+    wrapper.vm.selectWidget([wrapper.vm.sitemap.slots.widgets[0], wrapper.vm.sitemap])
+    await wrapper.vm.$nextTick()
+    localVue.set(wrapper.vm.selectedWidget.config, 'minValue', 5)
+    wrapper.vm.validateWidgets()
+    expect(lastDialogConfig).toBeFalsy()
+
+    // configure a minValue less to maxValue, should validate
+    lastDialogConfig = null
+    wrapper.vm.selectWidget([wrapper.vm.sitemap.slots.widgets[0], wrapper.vm.sitemap])
+    await wrapper.vm.$nextTick()
+    localVue.set(wrapper.vm.selectedWidget.config, 'minValue', 1)
+    wrapper.vm.validateWidgets()
+    expect(lastDialogConfig).toBeFalsy()
+  })
+
   it('validates mappings', async () => {
     wrapper.vm.selectWidget([wrapper.vm.sitemap, null])
     await wrapper.vm.$nextTick()
diff --git a/bundles/org.openhab.ui/web/src/pages/settings/pages/sitemap/sitemap-edit.vue b/bundles/org.openhab.ui/web/src/pages/settings/pages/sitemap/sitemap-edit.vue
index 45944032e6..dd295c0003 100644
--- a/bundles/org.openhab.ui/web/src/pages/settings/pages/sitemap/sitemap-edit.vue
+++ b/bundles/org.openhab.ui/web/src/pages/settings/pages/sitemap/sitemap-edit.vue
@@ -82,7 +82,7 @@
 
         <f7-actions ref="widgetTypeSelection" id="widget-type-selection" :grid="true">
           <f7-actions-group>
-            <f7-actions-button v-for="widgetType in widgetTypes" :key="widgetType.type" @click="addWidget(widgetType.type)">
+            <f7-actions-button v-for="widgetType in addableWidgetTypes" :key="widgetType.type" @click="addWidget(widgetType.type)">
               <f7-icon :f7="widgetType.icon" slot="media" />
               <span>{{ widgetType.type }}</span>
             </f7-actions-button>
@@ -264,6 +264,24 @@ export default {
       if (!this.selectedWidget) return false
       if (this.linkableWidgetTypes.indexOf(this.selectedWidget.component) < 0) return false
       return true
+    },
+    addableWidgetTypes () {
+      if (!this.selectedWidget) return
+      // No frames in frame
+      if (this.selectedWidget.component === 'Frame') return this.widgetTypes.filter(w => w.type !== 'Frame')
+      // Linkable widget types only contain frames or none at all
+      if (this.linkableWidgetTypes.includes(this.selectedWidget.component)) {
+        if (this.selectedWidget.slots && this.selectedWidget.slots.widgets && this.selectedWidget.slots.widgets.length > 0) {
+          if (this.selectedWidget.slots.widgets.find(w => w.component === 'Frame')) {
+            return this.widgetTypes.filter(w => w.type === 'Frame')
+          } else {
+            return this.widgetTypes.filter(w => w.type !== 'Frame')
+          }
+        } else {
+          return this.widgetTypes
+        }
+      }
+      return this.widgetTypes
     }
   },
   watch: {
@@ -362,6 +380,7 @@ export default {
     },
     validateWidgets (stay) {
       if (this.sitemap.slots && Array.isArray(this.sitemap.slots.widgets)) {
+        let validationWarnings = []
         const widgetList = this.sitemap.slots.widgets.reduce(function iter (widgets, widget) {
           widgets.push(widget)
           if (widget.slots && Array.isArray(widget.slots.widgets)) {
@@ -369,17 +388,32 @@ export default {
           }
           return widgets
         }, [])
-        let validationWarnings = []
-        widgetList.filter(widget => this.widgetTypesRequiringItem.includes(widget.component)).forEach(widget => {
-          if (!(widget.config && widget.config.item)) {
+        let isFrame = [false]
+        let siblingIsFrame = [undefined]
+        this.sitemap.slots.widgets.forEach(function iter (widget) {
+          if (isFrame[isFrame.length - 1] && widget.component === 'Frame') {
             let label = widget.config && widget.config.label ? widget.config.label : 'without label'
-            validationWarnings.push(widget.component + ' widget ' + label + ', no item configured')
+            validationWarnings.push('Frame widget ' + label + ', frame not allowed in frame')
+          }
+          if (siblingIsFrame[siblingIsFrame.length - 1] !== undefined) {
+            if ((siblingIsFrame[siblingIsFrame.length - 1] && (widget.component !== 'Frame')) || (!siblingIsFrame[siblingIsFrame.length - 1] && (widget.component === 'Frame'))) {
+              let label = widget.config && widget.config.label ? widget.config.label : 'without label'
+              validationWarnings.push('Widget ' + label + ', only frames or no frames at all allowed in linkable widget')
+            }
+          }
+          siblingIsFrame.push(siblingIsFrame.pop() || widget.component === 'Frame')
+          if (widget.slots && Array.isArray(widget.slots.widgets)) {
+            isFrame.push(widget.component === 'Frame')
+            siblingIsFrame.push(undefined)
+            widget.slots.widgets.forEach(iter)
+            isFrame.pop()
+            siblingIsFrame.pop()
           }
         })
-        widgetList.filter(widget => widget.component === 'List').forEach(widget => {
-          if (!(widget.config && widget.config.separator)) {
+        widgetList.filter(widget => this.widgetTypesRequiringItem.includes(widget.component)).forEach(widget => {
+          if (!(widget.config && widget.config.item)) {
             let label = widget.config && widget.config.label ? widget.config.label : 'without label'
-            validationWarnings.push(widget.component + ' widget ' + label + ', no separator configured')
+            validationWarnings.push(widget.component + ' widget ' + label + ', no item configured')
           }
         })
         widgetList.filter(widget => widget.component === 'Video' || widget.component === 'Webview').forEach(widget => {
@@ -389,17 +423,27 @@ export default {
           }
         })
         widgetList.filter(widget => widget.component === 'Chart').forEach(widget => {
-          if (!(widget.config && widget.config.period)) {
+          if (!(widget.config && widget.config.period && ['h', '4h', '8h', '12h', 'D', '2D', '3D', 'W', '2W', 'M', '2M', '3M', 'Y'].includes(widget.config.period))) {
             let label = widget.config && widget.config.label ? widget.config.label : 'without label'
-            validationWarnings.push(widget.component + ' widget ' + label + ', no period configured')
+            validationWarnings.push(widget.component + ' widget ' + label + ', invalid period configured: ' + widget.config.period)
           }
         })
         widgetList.filter(widget => widget.component === 'Input').forEach(widget => {
-          if (!(widget.config && widget.config.inputHint && ['text', 'number', 'date', 'time', 'datetime'].includes(widget.config.inputHint))) {
+          if (widget.config && widget.config.inputHint && !['text', 'number', 'date', 'time', 'datetime'].includes(widget.config.inputHint)) {
             let label = widget.config && widget.config.label ? widget.config.label : 'without label'
             validationWarnings.push(widget.component + ' widget ' + label + ', invalid inputHint configured: ' + widget.config.inputHint)
           }
         })
+        widgetList.filter(widget => widget.component === 'Slider' || widget.component === 'Setpoint').forEach(widget => {
+          if (widget.config && (widget.config.step !== undefined) && (widget.config.step <= 0)) {
+            let label = widget.config && widget.config.label ? widget.config.label : 'without label'
+            validationWarnings.push(widget.component + ' widget ' + label + ', step size cannot be 0 or negative: ' + widget.config.step)
+          }
+          if (widget.config && (widget.config.minValue !== undefined) && (widget.config.maxValue !== undefined) && (widget.config.minValue > widget.config.maxValue)) {
+            let label = widget.config && widget.config.label ? widget.config.label : 'without label'
+            validationWarnings.push(widget.component + ' widget ' + label + ', minValue must be less than or equal maxValue: ' + widget.config.minValue + ' > ' + widget.config.maxValue)
+          }
+        })
         widgetList.forEach(widget => {
           if (widget.config) {
             Object.keys(widget.config).filter(attr => ['mappings', 'visibility', 'valuecolor', 'labelcolor', 'iconcolor'].includes(attr)).forEach(attr => {
@@ -416,9 +460,10 @@ export default {
         })
         if (validationWarnings.length > 0) {
           this.$f7.dialog.create({
+            cssClass: 'sitemap-validation-dialog',
             title: 'Validation errors',
             text: 'Sitemap definition has validation errors:',
-            content: '<ul style="max-height: 100px; overflow-y: scroll"><li>' + validationWarnings.join('</li><li>') + '</li></ul>',
+            content: '<ul style="max-height: 200px; overflow-y: scroll"><li>' + validationWarnings.join('</li><li>') + '</li></ul>',
             buttons: [
               { text: 'Cancel', color: 'gray', close: true },
               { text: 'Save Anyway', color: 'red', close: true, onClick: () => this.save(stay, true) }