Prevent deselect a row after clicked same row second time on a b-table - bootstrap-vue

Question

how to prevent deselect a row from a bootstrap b-table?
at intialial state, no rows selected, but after the table is clicked, there is at least and at most 1 row selected. By default, clicking a row 2nd time, it will be deselected. I hope the selected row is still highlighted.
This table is not read-only, instead cells are given editors to support editing, so when current editing row is clicked again, the row must be still highlighted to support cell-editor's events fired correctly.
Background:
This is my template code, cell editor definition is injected via "<slot name="columns" />", and is initialized / cached in 'fields' during 'created' hook.
Method clicked() just write down current row index and process data, when current highlight row is clicked twice, its focus lost.
Sample layout:
<template>
<div>
<b-table ref="ui" :items="val" :fields="fields" responsive sticky-header head-variant="dark" :striped="true"
selectable select-mode="single" #row-clicked="clicked"
:data-meta="$attrs.name" v-bind="{...$attrs}" data-ui="16" :style="style" class="w-100 mx-0"
v-contextmenu:ctxMenu >
<slot name="events" />
<slot name="columns" />
<template #table-colgroup="scope">
<col v-for="(field, index) in scope.fields" :key="field.key" :style="field.visible ? index > 0 && field.sz === undefined ? null : (index == 0 ? 'nowrap: nowrap' : ('width: ' + field.sz + 'ch!important')) : 'width: 0!important'" />
</template>
<template v-for="(field, index) in fields" v-slot:[cell(field.key)] = "row">
<table :key="index" :style="index == 0 ? 'width: 20ch' : null" v-if="index == 0" style="p-0">
<tbody>
<tr #click="clickTreeRow(row.index, row.item)">
<td class="m-0 p-0">
<a :key="index" v-if="index === 0" variant="primary" href="#" #click.prevent="switchNode(row.item)" :style="'padding-left:' + row.item.level + 'em'" >
<b-icon :icon="row.item.children.length == 0 ? '' : row.item.expand ? 'folder-minus' : 'folder-plus'"/>
</a>
</td>
<td style="display: inline-block; white-space: nowrap" class="m-0 p-0">
<ui-text :key="'c' + row.index + '_' + field.key" :name="field.key" :type="field.type" :data-options="colOpt(field.key)" :data-default="colDef(field.key)" :data-param="colParam(field.key)" :layout="colLayout(field.key)" :sz="field.sz" :scale="field.scale" :data-row="row.index" #click="clicked(row, row.index)" #change="change" :cellEvents="columnEvents[field.key]" :class="fieldClazz" v-if="field.ui=='2'" />
<ui-combo :key="'c' + row.index + '_' + field.key" :name="field.key" :data-options="colOpt(field.key)" :data-default="colDef(field.key)" :data-param="colParam(field.key)" :layout="colLayout(field.key)" :sz="field.sz" :data-row="row.index" #click="clicked(row, row.index)" #change="change" :cellEvents="columnEvents[field.key]" :class="fieldClazz" v-else-if="field.ui === '9'" />
<ui-check :key="'c' + row.index + '_' + field.key" :name="field.key" :data-default="colDef(field.key)" :data-param="colParam(field.key)" :layout="colLayout(field.key)" :sz="field.sz" :data-row="row.index" #click="clicked(row, row.index)" #change="change" :cellEvents="columnEvents[field.key]" :class="checkClazz" v-else-if="field.ui === '12'" />
<ui-calendar :key="'c' + row.index + '_' + field.key" :name="field.key" :data-default="colDef(field.key)" :data-param="colParam(field.key)" :layout="colLayout(field.key)" :sz="field.sz" :data-row="row.index" #click="clicked(row, row.index)" #change="change" :cellEvents="columnEvents[field.key]" :class="fieldClazz" v-else-if="field.ui =='36'" />
<ui-textarea :key="'c' + row.index + '_' + field.key" :name="field.key" :data-default="colDef(field.key)" :data-param="colParam(field.key)" :layout="colLayout(field.key)" :sz="field.sz" :data-row="row.index" #click="clicked(row, row.index)" #change="change" :cellEvents="columnEvents[field.key]" :class="fieldClazz" v-else-if="field.ui =='10'" />
<ui-label :key="'c' + row.index + '_' + field.key" :name="field.key" :type="field.type" :layout="colLayout(field.key)" :sz="field.sz" :data-row="row.index" #click="clicked(row, index)" :class="fieldClazz" v-else />
</td>
</tr>
</tbody>
</table>
<ui-text :key="'c' + row.index + '_' + field.key" :name="field.key" :type="field.type" :data-options="colOpt(field.key)" :data-default="colDef(field.key)" :data-param="colParam(field.key)" :layout="colLayout(field.key)" :sz="field.sz" :data-row="row.index" #click="clicked(row, row.index)" #change="change" :cellEvents="columnEvents[field.key]" :class="fieldClazz" v-if="index > 0 && field.ui=='2'" />
<ui-combo :key="'c' + row.index + '_' + field.key" :name="field.key" :data-options="colOpt(field.key)" :data-default="colDef(field.key)" :data-param="colParam(field.key)" :layout="colLayout(field.key)" :sz="field.sz" :data-row="row.index" #click="clicked(row, row.index)" #change="change" :cellEvents="columnEvents[field.key]" :class="fieldClazz" v-else-if="index > 0 && field.ui === '9'" />
<ui-check :key="'c' + row.index + '_' + field.key" :name="field.key" :data-default="colDef(field.key)" :data-param="colParam(field.key)" :layout="colLayout(field.key)" :sz="field.sz" :data-row="row.index" #click="clicked(row, row.index)" #change="change" :cellEvents="columnEvents[field.key]" :class="checkClazz" v-else-if="index > 0 && field.ui === '12'" />
<ui-calendar :key="'c' + row.index + '_' + field.key" :name="field.key" :data-default="colDef(field.key)" :data-param="colParam(field.key)" :layout="colLayout(field.key)" :sz="field.sz" :data-row="row.index" #click="clicked(row, row.index)" #change="change" :cellEvents="columnEvents[field.key]" :class="fieldClazz" v-else-if="index > 0 && field.ui =='36'" />
<ui-textarea :key="'c' + row.index + '_' + field.key" :name="field.key" :data-default="colDef(field.key)" :data-param="colParam(field.key)" :layout="colLayout(field.key)" :sz="field.sz" :data-row="row.index" #click="clicked(row, row.index)" #change="change" :cellEvents="columnEvents[field.key]" :class="fieldClazz" v-else-if="index > 0 && field.ui =='10'" />
<ui-label :key="'c' + row.index + '_' + field.key" :name="field.key" :type="field.type" :layout="colLayout(field.key)" :sz="field.sz" :data-row="row.index" #click="clicked(row, index)" :class="fieldClazz" v-else-if="index > 0" />
</template>
</b-table>
<v-contextmenu ref="ctxMenu" theme="dark">
<v-contextmenu-item #click="addNode()" :disabled="availableActions[0] === false">+</v-contextmenu-item>
<v-contextmenu-item #click="removeNode()" :disabled="availableActions[1] === false">-</v-contextmenu-item>
<v-contextmenu-item divider></v-contextmenu-item>
<v-contextmenu-item #click="move('U')" :disabled="availableActions[2] === false">↑</v-contextmenu-item>
<v-contextmenu-item #click="move('D')" :disabled="availableActions[3] === false">↓</v-contextmenu-item>
<v-contextmenu-item #click="move('L')" :disabled="availableActions[4] === false">←</v-contextmenu-item>
<v-contextmenu-item #click="move('R')" :disabled="availableActions[5] === false">→</v-contextmenu-item>
</v-contextmenu>
</div>
</template>
<script>